Bryant propane heater can't possibly be wired reversed (red LED blinks constantly)

[Danny D.]

Troubleshooting advice requested, because the LED blinking
constantly supposedly indicates that the heater is wired
in reverse (which really isn't very likely, so I must be
misinterpreting something obvious).

Heater worked last year (AFAIK).

It just started getting cold in California, so, the heater power
was turned on, and ... and ... and ... uh ... um ... no heat.
https://c4.staticflickr.com/8/7508/15874015487_954311f464_k.jpg

Thermostat batteries are good:
https://c1.staticflickr.com/9/8595/15872500000_fd3c98abbd_k.jpg

Heater power is on and the blower blows but the red led blinks
at a steady pace forever.
https://c4.staticflickr.com/8/7513/16057827501_184a54e186_c.jpg

Checked that the switches inside were all on:
https://c4.staticflickr.com/8/7510/15437487484_e1c399d625_b.jpg

Checked that the fuse on the circuit board was good:
https://c1.staticflickr.com/9/8672/16059787345_1a4a6d21f8_c.jpg

The sticker says constant flashes indicates reverse wiring:
https://c4.staticflickr.com/8/7505/15872330868_8d4f42e6c5_c.jpg

But, there's no way the wiring was changed between last year & now.
https://c4.staticflickr.com/8/7540/15437487004_282d8775fe_c.jpg

Here's what it looks like inside:
https://c4.staticflickr.com/8/7561/16059787745_b47f78bee3_b.jpg
https://c1.staticflickr.com/9/8561/15437487674_007cc1f787_b.jpg

I don't know where the model number is, so, I don't have a manual
yet.

Debugging suggestions are requested, and very helpful. Thanks!

[Stormin Mormon]

Model number inside the case, in your machine
probably on the inner ceiling. As to reverse
polarity, you'd have to use a VOM to confirm
the black is hot, white is neutral.

-
.
Christopher A. Young
Learn about Jesus
www.lds.org
.

[trader_4]

According to that secret decoder table, it tells you what's wrong
by blinking short blinks, followed by long blinks. Those continue
indefinitely, in a pattern. So, are you saying it's not doing that,
but instead it's giving you no pattern, just rapid flashes, which
the table says is reversed polarity?

If so, best guess would be that the oontroller board is kaput. Did you
have that flakey generator running it?

[Danny D.]

trader_4 wrote, on Fri, 19 Dec 2014 16:14:54 -0800:

> According to that secret decoder table, it tells you what's wrong
> by blinking short blinks, followed by long blinks. Those continue
> indefinitely, in a pattern. So, are you saying it's not doing that,
> but instead it's giving you no pattern, just rapid flashes, which
> the table says is reversed polarity?

Here is exactly what the blinking is doing with the cover off
and me pressing on the door switch manually:
https://www.flickr.com/photos/98287134@N02/15438398234/

This is the secret decoder ring in a full-size JPEG file:
https://c4.staticflickr.com/8/7484/16058751021_b55d624fe0_c.jpg

What do you make of those blinks with the cover off the unit?

[Danny D.]

Stormin Mormon wrote, on Fri, 19 Dec 2014 19:13:20 -0500:

> Model number inside the case, in your machine
> probably on the inner ceiling. As to reverse
> polarity, you'd have to use a VOM to confirm
> the black is hot, white is neutral.

Thanks for that advice.

I can check the polarity, but, really, there's no way
it changed.

So, I must be interpreting the flashes incorrectly.

Here is the full-size secret decoder ring:
https://c4.staticflickr.com/8/7484/16058751021_b55d624fe0_c.jpg

Given that, what do folks make of these flashes in
this 30-second video while the cover was still on the unit?
https://www.flickr.com/photos/98287134@N02/16060716735/

[Stormin Mormon]

On 12/19/2014 10:21 PM, Danny D. wrote:
>
> Here is exactly what the blinking is doing with the cover off
> and me pressing on the door switch manually:
> https://www.flickr.com/photos/98287134@N02/15438398234/
>
> This is the secret decoder ring in a full-size JPEG file:
> https://c4.staticflickr.com/8/7484/16058751021_b55d624fe0_c.jpg
>
> What do you make of those blinks with the cover off the unit?
>

I could not tell if it was continuous, or blinking 11.

In any case, and open ground can some times
give a fault code. I'd get out the VOM, and
check for polarity and also check for open
ground.

[Danny D.]

Stormin Mormon wrote, on Sat, 20 Dec 2014 06:01:41 -0500:

> I could not tell if it was continuous, or blinking 11.

If it's 11, then that corresponds to the following (which I don't
understand).
11: NO PREVIOUS CODE - Stored status codes are erased when power
(115V or 24V) to control is interrupted or 48 hours after each
fault is cleared

What does that mean?

[Danny D.]

Stormin Mormon wrote, on Sat, 20 Dec 2014 06:01:41 -0500:

> I could not tell if it was continuous, or blinking 11.

If it's continuous, that corresponds to:
RAPID FLASHING - Line voltage (115V) polarity reversed.
If twinned, refer to twinning kit instructions.

What does "twinned" mean?

[trader_4]

The video wouldn't play in Internet Explorer, just sound. In Chrome
it played for me and clearly it shows 1 long flash, 5 short flashes,
followed by continuous flashes. The other video, with the door on,
just shows it flashing continously, no patterm.

Two problems. First the table says the codes are given by the number
of long flashes and short flashes, which would lead you to believe
the long flashes should come first, not the other way around.

Second, no matter, there is no table entry for 1-5 or 5-1.

The continous flashing with the cover on, in the other video, I would
agree looks like line polarity reversed. Which for a previously installed
furnace would appear to be virtually impossible. Another possibility
would be that the control board was replaced previously with a different
type that has different codes.

So, I agree, I'd check with a VOM to make sure AC is in order. After
that, IDK. We don't know the sequence of what comes before those videos.
If the furnace winds up with that constant blinking in the first video
right after power has been removed, then turned back on, I'd say it's
most likely the control board. If the light is just on steady, which I
think is normal condition, and then when it goes to *fire*, he gets the
1 -5 sequence, then I'd say it's more likely something else, ie that it's
detecting something wrong, like pressure, when purging. But why it's not
in the list, the blinks seem backward, I guess that's just par for the
course with the stuff at D's house.

[Danny D.]

trader_4 wrote, on Sat, 20 Dec 2014 05:19:01 -0800:

> The video wouldn't play in Internet Explorer, just sound. In Chrome
> it played for me and clearly it shows 1 long flash, 5 short flashes,
> followed by continuous flashes. The other video, with the door on,
> just shows it flashing continously, no patterm.

Thanks for taking a look at it, because I saw exactly the same thing.

The video with the door on was taken after it was running for ten or
fifteen minutes, but with no heat, so I crawled into the crawlspace
where the heater was and taped the flashing.

There was nothing whatsoever done with the line voltage of this
furnace, at least not on purpose. No electricians came to the house.
And nothing was done on the furnace whatsoever.

So, for the line voltage to reverse, that would be odd.

> Two problems. First the table says the codes are given by the number
> of long flashes and short flashes, which would lead you to believe
> the long flashes should come first, not the other way around.

I can't tell if the continuous flashes are long or short.

> Second, no matter, there is no table entry for 1-5 or 5-1.

I did see, as you saw, that the first few seconds of flashes
were not the same as the rest of the flashes. I didn't know what
to make of it, but you discerned a 1-5, which makes your timing
better than mine.

> Another possibility would be that the control board was replaced
> previously with a different type that has different codes.

Ah. I understand what you're saying. If the control board doesn't
match the cover secret decoder ring, then that might explain a lot.

> We don't know the sequence of what comes before those videos.

I'll snap a new "reboot" video today, with the power turned off to
the furnace, for a few hours, and then turned back on and started
right up so we get the "initial" sequence of flashes.

[trader_4]

It doesn't have to be turned off for a few hours, just turned off and
back on. Record what it does when power comes back on without a call for
heat. If it shows normal, stays that way for a few mins, then turn
up the thermostat and see what happens.

Another thing, you're not operating the furnace normally. You have the
cover off, furnace powered up and you're depressing the door safety switch
to initite it. For all we know that 1 -5 sequence could mean "detected
door switch open". Power it up with the door switch closed, either with
the door on, tape over it, etc.

[Zak W]

"Danny D." <dannyd...@gmail.com> wrote in news:m73ter$o70$1@dont-
email.me:

>> Second, no matter, there is no table entry for 1-5 or 5-1.
>

The way I see it is that you may need a new controler.

[Stormin Mormon]

Means that either someone turned off the power
(so the unit lost its memory kind of like a VCR
blinking 12:00) or that the fault was so long
ago, that the unit lost its memory.

In any case, please try shutting off the power
for 30 seconds or so, and turn it back on. Some
times that handles nussiance trips.

[Terry Coombs]

He might try blowing the control board off with compressed air . Dust , if
damp , can short circuit those miniscule signals ... as I found out after
buying a new board for my Goodman furnace . Now I have a spare .

--
Snag

[Tony Hwang]

Hi,
I believe it is code 33. I am pretty sure.

[Danny D.]

Tony Hwang wrote, on Sat, 20 Dec 2014 19:41:51 -0700:

> I believe it is code 33. I am pretty sure.

Thanks for looking as it's really hard to tell what the
blinking indicates.

If it's 33, then that corresponds to:

LIMIT OR FLAME ROLL-OUT SWITCH IS OPEN-
If open longer than three minutes, code changes to #13.
Check for:
- Defective blower motor or start capacitor
- Loose blower wheel
- Inadequate combustion air supply flame roll-out switch or fuse link
- Open flame roll-out switch, or fuse link. Manual reset or replace.
- Dirty filter or restricted duct system
- Defective switch or connections

I'm not sure I understand all of those, but some are easy,
e.g., I'll look for whereever the filter is (which has never
been cleaned to my knowledge).

[mako...@yahoo.com]

Some of these controllers sense the small electrical conductivity of a fire as a flame sensor. Since the fire is grounded, the flame sense ciccuot senses to earth ground. To do that, the conntroller needs a good earth ground and it gets that through the ac connection. All 3 wires of the ac connection have to be correct. The black has to be hot. The white neutral and the green or bare ground. Check that these 3 connections are correct, including the ground connection. Also chech that these is no sign of water on the electronics. Also chcck the flame sensorrobe wire is not shorted or has water.

Mark

[Danny D.]

The area is in a crawlspace that is *above* the house, so,
it's pretty dry. At least, I don't see any moisture anywhere,
even though it has been raining (thank God) outside.

[Stormin Mormon]

If this is the trouble code, you most likely have
not enough air flow through the furnace, and the
furnace is over heating. You might also have a
clogged flue.

First step is to seek for the air filter, and replace
it. Also see if the blower wheel spins while the furnace
is on, and calling for heat.

--

[Danny D.]

Stormin Mormon wrote, on Sat, 20 Dec 2014 09:45:08 -0500:

> In any case, please try shutting off the power
> for 30 seconds or so, and turn it back on. Some
> times that handles nussiance trips.

I turned the power off and then after a few minutes, back on.
Nothing changed.

I tried to check voltages, but I don't know what to test:
https://c4.staticflickr.com/8/7550/15887993238_efabb172d6_b.jpg

The model is Bryant 373LAV024070, input 69,000BTU, output 66,000 BTU:
https://c4.staticflickr.com/8/7568/15888147220_508fa24051_b.jpg

[Danny D.]

trader_4 wrote, on Sat, 20 Dec 2014 05:37:54 -0800:

> It doesn't have to be turned off for a few hours, just turned off and
> back on. Record what it does when power comes back on without a call for
> heat. If it shows normal, stays that way for a few mins, then turn
> up the thermostat and see what happens.

I turned off the power.
Put the covers back on.
Turned the power back on.
Waited about 20 minutes.
Turned it off for a few minutes.
Turned it back on.
Set the heat to HOLD at 80 degrees.
The blinking lights don't seem to have changed.

Here is the latest blinking light - which is odd as it stumbles
at 24 seconds, but I don't know what to make of that anomaly.
https://www.flickr.com/photos/98287134@N02/15889437369/

[Danny D.]

Tony Hwang wrote, on Sat, 20 Dec 2014 19:41:51 -0700:

> I believe it is code 33. I am pretty sure.

I found where to get manuals but I can't find the exact model:
http://www.bryant.com/apps/finddocs/form.jsp?b=b

The model is a Bryant 373LAV024070 (AGJA).
https://c4.staticflickr.com/8/7568/15888147220_508fa24051_b.jpg

The closest Bryant PDF manual I can find is:
373LAV 376CAV Downflow/Horizontal and 383KAV 395CAV Upflow Gas Furnace
http://dms.hvacpartners.com//docs/1009/Public/0B/OM04-35.pdf

383KAV Upflow Gas Furnace 373LAV Downflow Horizontal Gas Furnace
http://dms.hvacpartners.com//docs/1010/Public/00/BY-4383_373-005.pdf

I'll call Bryant on Monday to figure out why I can't find the
exact model in the lists of documents:
800-428-4326 from 5:00am-2:00pm (Pacific) weekdays.

[Danny D.]

Stormin Mormon wrote, on Sun, 21 Dec 2014 18:39:15 -0500:

> First step is to seek for the air filter, and replace
> it.

I opened up all the vents, and removed all the filters.
https://c4.staticflickr.com/8/7576/15453125224_2feb92f0c2_b.jpg

> Also see if the blower wheel spins while the furnace
> is on, and calling for heat.

Is this the "blower wheel"?
https://c4.staticflickr.com/8/7471/16049627356_c4173421dd_b.jpg

It spins freely manually (but never turns when the blower is
running).

I also replaced the batteries, in the controller, even though
they had tested at 1.4VDC open circuit (the new ones are
1.6 volts open circuit).
https://c4.staticflickr.com/8/7534/15453124484_7712b21a95_b.jpg

[trader_4]

Instead of making it fire, what does it do/flash if you just power it up with no call for heat?

[trader_4]

You have the model. The last numbers are the specific size and output. 24 may be width, 70k btus?

[Danny D.]

trader_4 wrote, on Sun, 21 Dec 2014 22:40:38 -0800:

> Instead of making it fire, what does it do/flash if you just power it up
> with no call for heat?

It appears to do the same thing, but I need to test further.

[trader_4]

Then it's nothing to do with it failing to ignite, overheating, gas
supply, etc. It;'s detecting something wrong with just the application
of power, without it even having a call for heat, trying to fire, etc.

Could be some sensor input is lacking, but then you'd think it would be
flashing a code that was in the table. Given what it's doing, my first
suspicion would be that it's a bad control board. Did you put a meter on
it when power is first applied, verified that it has 120V, ground is OK,
etc?

[Stormin Mormon]

On 12/21/2014 7:41 PM, Danny D. wrote:
> Stormin Mormon wrote, on Sun, 21 Dec 2014 18:39:15 -0500:
>
>> First step is to seek for the air filter, and replace
>> it.
>
> I opened up all the vents, and removed all the filters.
> https://c4.staticflickr.com/8/7576/15453125224_2feb92f0c2_b.jpg
>

CY: Yow, that's cruddy. And it looks like the air
flow is blocked. Should be open. Is it possible some
one walled off the air vent?

>> Also see if the blower wheel spins while the furnace
>> is on, and calling for heat.
>
> Is this the "blower wheel"?
> https://c4.staticflickr.com/8/7471/16049627356_c4173421dd_b.jpg

CY: That indicated item is the inducer fan. I meant the
blower which should be about a foot diameter, and
about a foot long. Hope this picture arrives:
http://www.meci.com/ebay1/7350905-0510.jpg
If the air handler blower isn't running, the furnace
will over heat.

>
> It spins freely manually (but never turns when the blower is
> running).
>

CY: Spins freely is good. The black six inch diameter
counter weight should run when the furnace is calling
for heat. It moves air through the combustion chamber.
The six inch blower has to spin up to speed before the
gas valve opens.

> I also replaced the batteries, in the controller, even though
> they had tested at 1.4VDC open circuit (the new ones are
> 1.6 volts open circuit).
> https://c4.staticflickr.com/8/7534/15453124484_7712b21a95_b.jpg
>

CY: New batteries is a good idea.

[Stormin Mormon]

If you're safe with a VOM, here's the technique:
Where the BX cable comes in on top (right over
the inducer fan), it ties into the furnace inside
the small box inside the case of the furnace. You
can get into the small box, and check for polarity
and if the ground is connected.

I hesitate to suggest people open up safety boxes
and work with live power, some folks can't do that
safely. Prefer not to go into a lot of detail on
an open forum.

Open ground can cause problems, also.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 07:50:33 -0500:

>> https://c4.staticflickr.com/8/7576/15453125224_2feb92f0c2_b.jpg
>>
> CY: Yow, that's cruddy. And it looks like the air flow is blocked.
> Should be open. Is it possible some one walled off the air vent?

I stuck my hands in there, and the opening is above.
Plus, it used to work, and nobody has touched it since.

It *was* embarrassing when I saw that cruddy filter.

I almost didn't want to post a picture before I cleaned it.

According to the manual, there is supposedly a "v-shaped" set
of filters at the blower itself, but I haven't been able to
find them yet.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 07:50:33 -0500:

> CY: That indicated item is the inducer fan. I meant the blower which
> should be about a foot diameter, and about a foot long. Hope this
> picture arrives:
> http://www.meci.com/ebay1/7350905-0510.jpg
> If the air handler blower isn't running, the furnace will over heat.

I found that blower you show after looking at the manual:
http://dms.hvacpartners.com//docs/1009/Public/0B/OM04-35.pdf

Mine is apparently a "downflow" horizontal model (373LAV), whatever
"downflow" means (as opposed to "upflow" types).

I guess that this means that the air flows "down", which, in the
case of my furnace, is sidewise, I presume to the right (but I'm
just guessing since the direction of airflow isn't described in
the manual).

I called Bryant (at 800-428-4326x3), who confirmed the furnace
is a series G, which was built within the last 15 years, and
actually, based on the serial number, was built in 1999.

They will be sending me more detailed manuals, which I will
let you know when I get them.

[Stormin Mormon]

Some applications like mobile homes, the air
flows from top to bottom (downflow). Many houses
have furnace in the cellar, and are up flow,
meaning the conditioned air blows out the top.
In the horizontal, doesn't make much difference.

Anyhow, good luck and skill. I hesitate to do
much electrical coaching on an open list like
this.


--

[Danny D.]

trader_4 wrote, on Mon, 22 Dec 2014 03:57:10 -0800:

> Could be some sensor input is lacking, but then you'd think it would be
> flashing a code that was in the table. Given what it's doing, my first
> suspicion would be that it's a bad control board. Did you put a meter
> on it when power is first applied, verified that it has 120V, ground is
> OK, etc?

I agree with you that the first thing I need to test is power and
control inputs.

The sad thing is that I don't have a clue how to test that, as only
once before did I ever troubleshoot a furnace. I don't even remember
if it's AC or DC control inputs. Nor which color wires do what
(although I do remember that it's a standard, so, I can look that up).

I just received from Bryant two more PDF manuals, in addition to the
sparse 12-page 373 LAV Series G "User's Information Manual" that
I had already found, namely:
a. Installation Start-up, and Operating Instructions (24 pages)
b. Service and Maintenance Procedures (16 pages)

I can convert the PDF to JPEG and then post the JPG so you can read
them, but is there a way to just post the PDF for you to view them
to help interpret them?

[Stormin Mormon]

On 12/22/2014 9:30 AM, Danny D. wrote:
> The sad thing is that I don't have a clue how to test that, as only
> once before did I ever troubleshoot a furnace. I don't even remember
> if it's AC or DC control inputs. Nor which color wires do what
> (although I do remember that it's a standard, so, I can look that up).
>

Do you have some friends to call? Someone out
there has to know how to use a VOM.

[trader_4]

The thing is constantly flashing, which according to the table, is
polarity reversed. That's virtually impossible, but there could be
something wrong with the incoming AC. To test it with a VOM:

turn off power, usually via turning off the red safety toggle switch
that's mounted near the furnace.

get access to the incoming AC, remove wire nuts from hot and neutral,
but leave wires twisted together

make sure wires are in the air, not touching anything

then turn power switch back on

with VOM check for
120V from hot (black) to neutral (white).
120V from hot to ground (that tells you it's not reversed polarity and
that the ground is likely OK.
0V from neutral to ground

Then turn off power and put it back together.

You could also do it easier without removing wire nuts if you
can find hot/neutral identified on the control board. You could just
probe it there.

If you're unsure about any of that, or basic electric safety,
I agree with Stormin. Either call a friend in who is, or just call for service.

Besides, I'd bet 99% that nothing is wrong with the power.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 07:54:59 -0500:

> If you're safe with a VOM, here's the technique:

I'm perfectly fine with 120/220V and can easily work with my
Fluke 75 on the furnace. I just need to know what to check,
bearing in mind that it's not at first obvious where the power
comes in yet.

> You can get into the small box, and check for polarity and
> if the ground is connected.

I can't imagine that the power polarity has reversed, on its own,
but, as you note, I should check it (since the flashing is hard
to understand and one interpretation of the flashes might be that
the power polarity is reversed).

Of course, that only matters for DC, right?
So I'd need to know *where* the DC is coming from, since the line
voltage is AC (yes, I know a neutral isn't the same as a hot, nor
even the same as a ground, but, in terms of polarity, switching
a neutral with a hot shouldn't matter for AC motors or step-down
transformers (which I presume exist near the circuit board).

> I hesitate to suggest people open up safety boxes and work
> with live power, some folks can't do that safely. Prefer not
> to go into a lot of detail on an open forum.

I have no problem whatsoever working around power.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 09:28:15 -0500:

> Some applications like mobile homes, the air flows from
> top to bottom (downflow).

Based on the additional manuals supplied by Bryant today,
I can confirm the air flow comes from the blower at the left
(i.e., the top) and out the right (i.e., the bottom).
https://c4.staticflickr.com/8/7463/15458101824_f3a75d2197_b.jpg

[Stormin Mormon]

On 12/22/2014 10:36 AM, Danny D. wrote:
>
>> I hesitate to suggest people open up safety boxes and work
>> with live power, some folks can't do that safely. Prefer not
>> to go into a lot of detail on an open forum.
>
> I have no problem whatsoever working around power.
>

I check my hotmail adress every few days,
more often if I know an email is coming
from a friend.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 09:38:59 -0500:

> Do you have some friends to call? Someone out there has
> to know how to use a VOM.

Heh heh ...

I know how to use a DMM as well as anyone here knows how to
use one. I have had Simpson (analog) ammeters and voltmeters
since I was a young teen, when I was making my own resistance
testing equipment long before consumer DMMs were common.

My Fluke 75 is a good meter, which I've had for something
like 30 years. So, *using* a meter isn't at all a problem.

The problem is knowing what measurements to take.

To that end, this control board summary is a start:
https://c4.staticflickr.com/8/7511/16080413865_44a7b9a83c_h.jpg

As is this wiring control schematic:
https://c1.staticflickr.com/9/8616/16080409655_c1d2721b93_h.jpg

And, of course, as is the overall furnace circuit schematic:
https://c4.staticflickr.com/8/7560/15460746143_20e91c4626_b.jpg

All of which I'm new to, but, which I will print and pore over
to see what basic control and power inputs to test with my
trusty DMM.

[Danny D.]

trader_4 wrote, on Mon, 22 Dec 2014 06:51:01 -0800:

> Besides, I'd bet 99% that nothing is wrong with the power.

I'll check that the white (neutral) has no voltage difference
with green or bare (ground), and that the black (hot) has
line voltage (120VAC) to both the neutral and ground, but, like
you, I am 99.9% sure that can't possibly be the problem.

The problem is "probably" described in this flow chart though...
https://c4.staticflickr.com/8/7506/15894320489_b56bb628a5_c.jpg

[trader_4]

On Monday, December 22, 2014 10:36:41 AM UTC-5, Danny D. wrote:
> Stormin Mormon wrote, on Mon, 22 Dec 2014 07:54:59 -0500:
>
> > If you're safe with a VOM, here's the technique:
>
> I'm perfectly fine with 120/220V and can easily work with my
> Fluke 75 on the furnace. I just need to know what to check,
> bearing in mind that it's not at first obvious where the power
> comes in yet.
>
>

I've never seen a furnace where it's not obvious where the power
comes in. I'm beginning to agree with Stormin.

> You can get into the small box, and check for polarity and
> > if the ground is connected.
>
> I can't imagine that the power polarity has reversed, on its own,
> but, as you note, I should check it (since the flashing is hard
> to understand and one interpretation of the flashes might be that
> the power polarity is reversed).
>
> Of course, that only matters for DC, right?

No, you can reverse the hot and neutral on AC. But as I said
before, it's virtually impossible for that to have happened and
I doubt anything to do with the power to the furnace is the problem.

[Stormin Mormon]

On 12/22/2014 11:12 AM, Danny D. wrote:
> My Fluke 75 is a good meter, which I've had for something
> like 30 years. So, *using* a meter isn't at all a problem.
>
> The problem is knowing what measurements to take.
>
> To that end, this control board summary is a start:
> https://c4.staticflickr.com/8/7511/16080413865_44a7b9a83c_h.jpg
>
> As is this wiring control schematic:
> https://c1.staticflickr.com/9/8616/16080409655_c1d2721b93_h.jpg
>
> And, of course, as is the overall furnace circuit schematic:
> https://c4.staticflickr.com/8/7560/15460746143_20e91c4626_b.jpg
>
> All of which I'm new to, but, which I will print and pore over
> to see what basic control and power inputs to test with my
> trusty DMM.
>

Black is hot, white is neutral, and green is
ground. You test at the little box I mentioned
earlier.

If it's the 31 code, I suspect you've got a bad
limit switch, not enough air flow, and the limit
switch finally gave out. I've seen two of those,
this year so far.

[Stormin Mormon]

With that clogged air filter, I'd be thinking
bad thermal limit switch. I replaced one this
year in my own furnace, and one about a week
later for a customer.

[Danny D.]

trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

> I've never seen a furnace where it's not obvious where the power comes
> in. I'm beginning to agree with Stormin.

OK. Fair enough. I haven't looked hard enough mainly because
I really don't think the problem is a reversed polarity on the
AC circuit.

First off, the thing is AC, so, "most" AC items don't care
whether the hot or neutral are reversed anyway; but more
importantly, nothing was done to reverse the hot and neutral.

Looking at my pictures, clearly the line voltage comes in right
at the middle, from the overhanging flexible metal BX cable:
https://c4.staticflickr.com/8/7516/15440121993_72dc89861a.jpg

So, I'll pop off the cover of the box on the inside of that
connection - but - really - that will just tell me what I already
know must be the case - which is that the AC "line voltage" isn't
reversed.

But, I'll check it - and report back - with pictures.

[Stormin Mormon]

On 12/22/2014 11:21 AM, trader_4 wrote:
>> bearing in mind that it's not at first obvious where the power
>> comes in yet.
>>
>>
>
> I've never seen a furnace where it's not obvious where the power
> comes in. I'm beginning to agree with Stormin.
>

CY: Hello! BX cable on top, to small box.
Earth to Danny!

>>
>> Of course, that only matters for DC, right?
>
> No, you can reverse the hot and neutral on AC. But as I said
> before, it's virtually impossible for that to have happened and
> I doubt anything to do with the power to the furnace is the problem.
>

CY: I've seen reversed polarity, and also open
grounds.

>>> I hesitate to suggest people open up safety boxes and work
>>> with live power, some folks can't do that safely. Prefer not
>>> to go into a lot of detail on an open forum.
>>
>> I have no problem whatsoever working around power.
>

CY: Well, in that case, the job is completed,
and you can post about it.

[Danny D.]

trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

> No, you can reverse the hot and neutral on AC. But as I said before,
> it's virtually impossible for that to have happened and I doubt anything
> to do with the power to the furnace is the problem.

I agree that hot and neutral *can* be reversed, but, from a practical
standpoint, other than the safety of two-wire grounded items, it
makes no difference.

So, when they're talking polarity reversal in the continuous-blink
scenario, I wonder if they're talking about the DC voltage, where
polarity can make a huge difference.

I doubt either one was reversed, simply because nothing was touched,
but, methinks they may be talking DC and not AC anyway.

Nonetheless, I'll pop that box off in the middle of the furnace
and measure the voltages (yes, I know what all the colors mean,
including white, black, red, if it's there, and green or bare).

I didn't check if it's 220V, but that just means there will be
two hots and a neutral, instead of a hot and a neutral.

[trader_4]

On Monday, December 22, 2014 11:34:27 AM UTC-5, Danny D. wrote:
> trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:
>
> > No, you can reverse the hot and neutral on AC. But as I said before,
> > it's virtually impossible for that to have happened and I doubt anything
> > to do with the power to the furnace is the problem.
>
> I agree that hot and neutral *can* be reversed, but, from a practical
> standpoint, other than the safety of two-wire grounded items, it
> makes no difference.
>
> So, when they're talking polarity reversal in the continuous-blink
> scenario, I wonder if they're talking about the DC voltage, where
> polarity can make a huge difference.
>

No, they are talking about polarity reversed at the incoming AC,
ie hot and neutral. How would you ever get DC reversed on the circuit
board?

[trader_4]

It's nothing to do with airflow. He says he gets the flashing
from the LEDs indicating a fault as soon as power is applied,
before there is even a call for heat.

[Stormin Mormon]

On 12/22/2014 11:29 AM, Danny D. wrote:
> Looking at my pictures, clearly the line voltage comes in right
> at the middle, from the overhanging flexible metal BX cable:
> https://c4.staticflickr.com/8/7516/15440121993_72dc89861a.jpg
>
> So, I'll pop off the cover of the box on the inside of that
> connection - but - really - that will just tell me what I already
> know must be the case - which is that the AC "line voltage" isn't
> reversed.
>
> But, I'll check it - and report back - with pictures.
>

We'd expect nothing less from the professional
you are.

[Stormin Mormon]

On my own furnace, I did get a fault code when
it powered up, and turned out to be a bad limit.

So my personal experience is.....

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 12:49:48 -0500:

>> But, I'll check it - and report back - with pictures.
> We'd expect nothing less from the professional you are.

I gathered the testing equipment:
https://c4.staticflickr.com/8/7541/15895478557_72ea2b8a1c_b.jpg

I turned off the wall switch (it's turned on in this pic):
https://c4.staticflickr.com/8/7498/16055449886_83481232cf_b.jpg

I removed the cover of the inlex box from the BX cable:
https://c4.staticflickr.com/8/7511/16055449596_ec594e782c_b.jpg

I separated the hot (black), neutral (white) & ground (green):
https://c4.staticflickr.com/8/7573/16055449486_771a9fd07a_b.jpg

Turning power on, I tested neutral to ground at 0 volts AC:
https://c4.staticflickr.com/8/7533/15893802108_8ba061993a_b.jpg

Turning power on, I tested hot to ground at nominally 120VAC.
https://c1.staticflickr.com/9/8638/16079317891_f08709828b_b.jpg

Turning power on, I tested hot to neutral at nominally 120VAC.
https://c4.staticflickr.com/8/7490/16055448766_887fb5ddc8_b.jpg

I turned the power off, and reconnected the wires as before.

If the power is reversed, it's not at the inlet BX cable
connection to the unit.

What I mostly want to find is the big red button that says
"reset", but I don't see it. I see a bunch of smaller limit
resets, all of which I've pressed already.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 11:31:41 -0500:

> CY: I've seen reversed polarity, and also open grounds.

The grounds seem good, tested from green to the metal case.
https://c1.staticflickr.com/9/8561/16081323115_c245432dbc_c.jpg

[mako...@yahoo.com]

>
> I agree that hot and neutral *can* be reversed, but, from a practical
> standpoint, other than the safety of two-wire grounded items, it
> makes no difference.
>

I suggest you read my previous post that explains how the flame sensor circuit works.

You can lead a horse to water......

Mark

[Danny D.]

trader_4 wrote, on Mon, 22 Dec 2014 08:37:51 -0800:

> No, they are talking about polarity reversed at the incoming AC,
> ie hot and neutral. How would you ever get DC reversed on the circuit
> board?

The incoming power, at least at the BX cable coming into the furnace,
is not reversed, but, clearly "something" is wrong, so I do
appreciate the advice as to what to look for.

A few things I did in the meantime, which "may" have changed the
situation is that I opened up all the vents in the house, most
of which had been closed for some reason (almost certainly since
last winter), which means the vent airflow was certainly stifled.

I opened all the suckers:
https://c4.staticflickr.com/8/7563/16081369415_75ca4af62b_b.jpg

And all the blowers:
https://c4.staticflickr.com/8/7478/16081369215_2ea422228b_b.jpg

And, I ascertained that there is no V-shaped filter in the top
(left) side of the furnace itself:
https://c4.staticflickr.com/8/7491/16081369455_3b8312f3fe_c.jpg

This lack of v-shaped filters is apparently normal, as it is
described on the furnace cover sticker, which says:
"Horizontal furnace: Filters are located external of furnace.
Consult installer for location."
https://c4.staticflickr.com/8/7474/15895316579_700f645731_c.jpg

Interestingly, since most of the vents were closed, I might assume
the furnace had shut off due to lack of air, but I can't find
what the sticker also says is the "RESET" button:
"Auxiliary limit control may be located on blower housing or
top of furnace. To RESET, push button on control firmly.
Refer to USERS MANUAL for more information. Call qualified
serviceman if failure continues."

Also, the sticker talks about a "fusible link", which I also
haven't found yet:
https://c1.staticflickr.com/9/8575/15893966958_dba6bf6b65_c.jpg
"This furnace is equipped with a fusible element or manual reset
limit switch in burnder compartment and/or draft diverter to
protect against overheat conditions that can result from
inadequate combustion air supply or blocked vent conditions."

Just in case, I hit all the reset buttons I could find, starting
with the two manual limit switches:
https://c4.staticflickr.com/8/7496/16080776572_77acc7329a_c.jpg

When I press the brown button on the manual limit switch, nothing
happens (I had expected a spring-loaded type of interaction):
https://c4.staticflickr.com/8/7490/15461819153_09550d1ee2_c.jpg

I pressed the brown button on the blocked vent tube switch:
https://c4.staticflickr.com/8/7580/16079557691_fd19b8f191_c.jpg

There were no buttons on the flame sensor and hot surface igniter,
so, I merely wiggled the wires to ensure they were on snugly:
https://c1.staticflickr.com/9/8651/16055688506_f47fe7ca9f_c.jpg

I suspect this is the backside of the fusible link, which likewise,
I wiggled the wires to ensure they were on tightly:
https://c4.staticflickr.com/8/7498/15459174234_614fb55b63_b.jpg

I also flipped the on-off switch, on the gas valve itself, a few times:
https://c1.staticflickr.com/9/8681/15894042378_89d011aced_c.jpg

I also wiggled all the wires and connections on the control board:
https://c1.staticflickr.com/9/8631/16080848032_984bb7c59e_c.jpg

I'll run another series of tests, and see if any of that made
a difference.

[Danny D.]

makolber wrote, on Mon, 22 Dec 2014 10:24:18 -0800:

> I suggest you read my previous post that explains how the flame sensor
> circuit works.
> You can lead a horse to water......
> Mark

Hi Mark,
I had read your suggestion and followed it as much as possible.

There is a flame sensor, and a hot igniter, which are located here:
https://c1.staticflickr.com/9/8651/16055688506_f47fe7ca9f_c.jpg

I don't know yet how to physically 'test' them, but they do not appear
to be damaged. There is absolutely no water, and the ground appears
good but I need to run more tests on ground to be doubly sure.

The good news is that, after wiggling everything and opening all the
vents, and replacing the batteries, I called for heat just now:
https://c4.staticflickr.com/8/7553/15895968407_691d83ee2a_b.jpg

First the first time all winter, the igniter lit after the blower
motor ran for a minute or so!
https://c4.staticflickr.com/8/7566/15894445560_61a8d7692c_c.jpg

Then, for the first time, the flame and igniter went on:
https://c4.staticflickr.com/8/7554/16081730675_3f38cbbba7_c.jpg

Then, just the flame went on, for about 10 seconds or so:
https://c4.staticflickr.com/8/7550/16079806881_c6b9901d66_c.jpg

This happened three times, in quick succession, and then the furnace
went back to the blinking.

I will post the blinking video separately, as it seems to be
blinking a different code now.

[Ralph Mowery]

"Danny D." <dannyd...@gmail.com> wrote in message
news:m79r6c$shf$5...@dont-email.me...

Now that all that went on, it might be time to check the air flow switch.
It will be something after the blower mounted on the air chamber. It is a
switch that will probably show open and when you have air flow it will
close. If it does show open, and never closes when the blower starts up,
you have low air flow. Either the blower is not turning or the switch could
be bad. If it shows open, hook the two wires together and see if the
furnace stays running. Or place your meter across the wires and see if they
stay closed. You can probably go to ground from one of the contacts and one
side will always have voltage and the other one will not. Get on the one
without the voltage and see if it ever gets the voltage.



---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 11:26:40 -0500:

> With that clogged air filter, I'd be thinking bad thermal limit switch.
> I replaced one this year in my own furnace, and one about a week later
> for a customer.

Partial success!

After all the fiddling, I'm finally getting the thermal igniter to
ignite, and the flames go on three times, and then shut off, so,
that's a partial success, I guess.

First, the LED was solid red for a minute or so:
https://www.flickr.com/photos/98287134@N02/16082030575/

But then, it quickly switched to what appeared to be a code #12:
https://www.flickr.com/photos/98287134@N02/16081998125/

Then, the flames went on three times and then off within seconds
with a resulting LED blinking code of what appears to be #34:
https://www.flickr.com/photos/98287134@N02/16081950225/

Given all those inconsistencies within the span of 15 minutes,
I'm not sure if things are changing or if there are more than
one problem or if the thing just needs to settle down, because
those blink codes are changing depending on what is happening
with the blower.
https://c4.staticflickr.com/8/7505/15872330868_8d4f42e6c5_c.jpg

The gas valve is definitely turned on, and there is plenty of
gas on the stove and in the 500 gallon propane tank.
https://c4.staticflickr.com/8/7508/15874015487_954311f464_k.jpg

I will doublecheck that the metal case is grounded, and, I will
sand or steel wool the flame sensor and check the amperage if my
Fluke 75 can get down that low.

34: Ignition proving failure: Control will try three more times
before a lockout #14 occurs. If flame signal lost after trial
for ignition period, blower will come on for 90-second
recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper)
- Proper flame sense microamps (0.5microamps DC minimum)
- Gas valve turned off (manual shutoff valve, low inlet gas pressure)
- Green wire MUST be connected to furnace sheet metal
- Inadequate flame carryover or rough ignition

14: Ignition Lockout: Control will auto-reset after three hours.
Refer to #34.

12: Blower on after power up: (115V or 24V) Blower runs for 90
seconds, if unit is powered up during a call for heat
(R-W closed).
https://c4.staticflickr.com/8/7545/16081024172_14d3f7f629_c.jpg

[trader_4]

It's not an air handler blower issue. He gets the flashing trouble
indication as soon as power is applied, without any call for heat, without
the furnace firing, without the blower ever starting.

[Ralph Mowery]

"trader_4" <tra...@optonline.net> wrote in message
news:ed30bf09-f70f-470c...@googlegroups.com...

>> It's not an air handler blower issue. He gets the flashing trouble
> indication as soon as power is applied, without any call for heat, without
> the furnace firing, without the blower ever starting.
>

He was getting that flashing , but he just said the heater tried to start
after he did all the resetting and checking later on.

The heater could have came on at the very start and failed. This could have
tripped a safety device and he finally reset it, only to have it fault again
on the restart attempt.

[trader_4]

On Monday, December 22, 2014 4:55:35 PM UTC-5, Ralph Mowery wrote:
> "trader_4" <tra...@optonline.net> wrote in message
> news:ed30bf09-f70f-470c...@googlegroups.com...
> >> It's not an air handler blower issue. He gets the flashing trouble
> > indication as soon as power is applied, without any call for heat, without
> > the furnace firing, without the blower ever starting.
> >
>
> He was getting that flashing , but he just said the heater tried to start
> after he did all the resetting and checking later on.

Again, "tried to start", is not an air handler blower problem. If the
blower failed, there were clogged filters, etc, the furnace would fire up.
run for several minutes, then shut off with a failure code.

>
> The heater could have came on at the very start and failed. This could have
> tripped a safety device and he finally reset it, only to have it fault again
> on the restart attempt.
>
>

Two problems with that:

1 - It has continous blinking, ie abnormal LED as soon as power is restored. It's not firing and then reporting a problem.

2 - If it fired at the very start and failed, it's also not a blower
problem. The blower typically comes on about 2 mins into the whole
startup. For it to reach an over temp and shut down, would require a
lot longer.

[Tony Hwang]

Hi,
First, I'd just clean the flame sensor to get one thing out of the way.
I never ran into failed sensor but dirty one which did not work well.
Rubbing it with emery cloth always made it work again.

[Danny D.]

Ralph Mowery wrote, on Mon, 22 Dec 2014 14:43:24 -0500:

> Now that all that went on, it might be time to check the air flow
> switch. It will be something after the blower mounted on the air
> chamber. It is a switch that will probably show open and when you have
> air flow it will close. If it does show open, and never closes when the
> blower starts up, you have low air flow. Either the blower is not
> turning or the switch could be bad. If it shows open, hook the two
> wires together and see if the furnace stays running. Or place your
> meter across the wires and see if they stay closed. You can probably go
> to ground from one of the contacts and one side will always have voltage
> and the other one will not. Get on the one without the voltage and see
> if it ever gets the voltage.

Do you think this might be the air-flow switch, bolted into the side
of the air chamber?
https://c4.staticflickr.com/8/7527/15896266830_a8d908b870_b.jpg

I tested it and it seems to be a short (which is probably what it
is supposed to be).
https://c4.staticflickr.com/8/7540/16057767126_a618ee847c_b.jpg

It might be a temperature switch though... or a fusible link?
https://c4.staticflickr.com/8/7498/15459174234_614fb55b63_b.jpg

[Danny D.]

Tony Hwang wrote, on Mon, 22 Dec 2014 15:58:34 -0700:

> First, I'd just clean the flame sensor to get one thing out of the way.
> I never ran into failed sensor but dirty one which did not work well.
> Rubbing it with emery cloth always made it work again.

The flame sensor is supposed to have 50 microamps, but I
couldn't measure that low with my Fluke 75 DMM:
https://c4.staticflickr.com/8/7463/15897514539_472757e870_b.jpg

So I removed the flame sensor to take a look at its condition:
https://c4.staticflickr.com/8/7475/15461298264_ee8647f174_b.jpg

That flame sensor was in surprisingly good shape, as is everything:
https://c4.staticflickr.com/8/7517/15461297864_ee71745c49_b.jpg

Even so, I steel wooled the small amount of oxide, just to be safe:
https://c4.staticflickr.com/8/7539/15897514139_25d5cf70c5_b.jpg

[Stormin Mormon]

Sounds properly polaraized. The big reset is usually
to switch off the AC power for several seconds.

--

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 11:24:38 -0500:

> Black is hot, white is neutral, and green is ground. You test at the
> little box I mentioned earlier.

I double checked all the grounds, and they're good.
https://c1.staticflickr.com/9/8597/15897546299_e662d59465_z.jpg

[Stormin Mormon]

Might have been someone, suggested low air
flow, and a bad limit switch. Trader, was
that you?

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 19:37:57 -0500:

> Sounds properly polaraized. The big reset is usually to switch off the
> AC power for several seconds.

While I have an AC on/off switch:
https://c4.staticflickr.com/8/7498/16055449886_83481232cf_b.jpg

I don't seem to have that big red button inside the blower compartment:
https://c4.staticflickr.com/8/7491/16081369455_3b8312f3fe_z.jpg

Yet, the manual implies that there can be an "AUXILIARY LIMIT SWITCH
(WHEN USED)"; but mine doesn't seem to have that switch.
https://c4.staticflickr.com/8/7541/16083707595_c44c0debcd_z.jpg

[Stormin Mormon]

On 12/22/2014 2:43 PM, Ralph Mowery wrote:
>
> Now that all that went on, it might be time to check the air flow switch.
> It will be something after the blower mounted on the air chamber. It is a
> switch that will probably show open and when you have air flow it will
> close. If it does show open, and never closes when the blower starts up,
> you have low air flow. Either the blower is not turning or the switch could
> be bad. If it shows open, hook the two wires together and see if the
> furnace stays running. Or place your meter across the wires and see if they
> stay closed. You can probably go to ground from one of the contacts and one
> side will always have voltage and the other one will not. Get on the one
> without the voltage and see if it ever gets the voltage.
>

With a new filter, and open vents, should
be much improved air flow. Lets see who
spots the non sequitor.

[Stormin Mormon]

On 12/22/2014 7:26 PM, Danny D. wrote:
>
> Do you think this might be the air-flow switch, bolted into the side
> of the air chamber?
> https://c4.staticflickr.com/8/7527/15896266830_a8d908b870_b.jpg
>
> I tested it and it seems to be a short (which is probably what it
> is supposed to be).
> https://c4.staticflickr.com/8/7540/16057767126_a618ee847c_b.jpg
>
> It might be a temperature switch though... or a fusible link?
> https://c4.staticflickr.com/8/7498/15459174234_614fb55b63_b.jpg
>
>

The thing with two rods, sleeves, and
what looks like a coin cell, is a thermal
cutout. It "should" be self resetting.
Continuity is good. Does not measure air
flow.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 20:16:27 -0500:

> The thing with two rods, sleeves, and what looks like a coin cell, is a
> thermal cutout. It "should" be self resetting. Continuity is good. Does
> not measure air flow.

Seems reasonable.

I don't know what measures air flow.

This is a "pressure sensor", with a black tube connected to the air
chamber; but I don't know how to test it yet:
https://c4.staticflickr.com/8/7516/16083184512_a446b2ae86_c.jpg

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 19:39:38 -0500:

> Might have been someone, suggested low air flow, and a bad limit
> switch. Trader, was that you?

Seems reasonable.

My hypothesis, at the moment, is that all the vents where shut
which (maybe) caused a "limit switch" to open up?

If only I could turn that limit switch back on.

I wish I could find a "master reset" which doesn't seem
to exist. I've pressed all the limit switch buttons I could
find already.

Here's the latest video after cleaning the flame sensor and
hooking up the DMM in DC amps mode at the 300ma range with
the flame sensor hooked in series with the DMM:
https://www.flickr.com/photos/98287134@N02/15464227533/

As before, the blower started up & then the induced draft motor
spun up, & then the igniter lit up orange, & then there were
flames which soon shut down. The flames happened three times,
all the while the LED blinked #34. When the flames died the
third time, the furnace shut down & the LED blinked #14.
https://c4.staticflickr.com/8/7521/16083106532_e632e0de5a_z.jpg

34 IGNITION PROVING FAILURE
- Control will try three more times before a lockout #14 occurs.

If flame signal lost after trial for ignition period, blower will

come on for 90 second recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper).
- Proper flame sense microamps (.5 microamps D.C. minimum).
- Gas valve turned off. - Manual shut-off valve. - Low inlet gas pressure.
- Green wire MUST be connected to furnace sheet metal.
- Inadequate flame carryover or rough ignition.

14 IGNITION LOCKOUT
- Control will auto-reset after three hours.
Refer to #34.

[Danny D.]

Stormin Mormon wrote, on Mon, 22 Dec 2014 20:11:18 -0500:

> With a new filter, and open vents, should be much improved air
> flow. Lets see who spots the non sequitor.

I'm not sure I understand ...

non sequitor === an inference that does not follow from the premises;
specifically : a fallacy resulting from a simple conversion of a
universal affirmative proposition or from the transposition of a
condition and its consequent.
- a statement (as a response) that does not follow logically from or is
not clearly related to anything previously said.

Anyway, I did *try* to run the "component test" as described here:
https://c4.staticflickr.com/8/7521/16083106532_e632e0de5a_c.jpg

COMPONENT TEST
To initiate the component test sequence,shut OFF the room
thermostat or disconnect the "R" thermostat lead. Briefly short
the TEST terminal to the ’Com 24V’ terminal. Status LED will flash
code and then turn ON the inducer motor. The inducer motor will
run for the entire component test. The hot surface ignitor,
blower motor-heat speed, and blower motor-cool speed will be
turned ON for 10-15 seconds each".

I first removed the RED wire from the (R) terminal block screw,
but when I held down the door switch and then at the same time I
touched the COM terminal to the TEST terminal, nothing happened:
https://c4.staticflickr.com/8/7554/15897783139_5108719d7e_b.jpg

So, I belatedly realized they must be talking about removing the
RED (R) terminal at the thermostat itself, so, put back the Red
wire onto the (R) terminal at the furnace, and then went down to
the thermostat and removed the two red wires from that thermostat.

Then, back up at the furnace, I added this orange wire to the COM
terminal so that I could hold down the door switch and then touch
the orange wire momentarily to the TEST blade on the control board:
https://c4.staticflickr.com/8/7560/15896583910_f7b61ec375_c.jpg

I'm not exactly sure what happened in this component test, but,
a bunch of things went on, and that was it. For example, the
inducer motor ran, and the igniter lit for a few seconds, but,
I didn't see anything else happen that told me any data.

Maybe I missed something in the so-called "component" test?

[Danny D.]

Danny D. wrote, on Fri, 19 Dec 2014 23:56:58 +0000:

> Debugging suggestions are requested, and very helpful. Thanks!

Here's where the Bryant 373LAV horizontal furnace stands tonight.

Blower starts, inducer motor starts, igniter starts, flame starts,
flame shuts down. Three times the igniter ignites the flame but
three times, the flame shuts down within seconds.

All the while it displays code #34.
At the end of the sequence, it shuts down and displays code #14.

Video:
https://www.flickr.com/photos/98287134@N02/15464227533/

Schematic:
https://www.flickr.com/photos/98287134@N02/15460746143/

Codes:
https://www.flickr.com/photos/98287134@N02/16083106532/

[trader_4]

Ok, so now the question that might shed some light on what's going on
is, what changed that allowed the furnace to get this far? Previously,
it would come up with a flashing LED trouble indication as soon as power
was put on, without firing at all. Now, it's firing, then shutting down
because it thinks it hasn't lit.

I think that may be relevant, because initially you had continous LED
flashes that the chart says corresponds to reversed polarity. While
the polarity isn't reveresed, I wonder if it will also give that code
if the ground is missing? I ask that because the flame sensor is
single wire and depends on a ground path back to the controller board.
Is it possible there is a bad ground connection between the controller
board and the furnace metal?

Other than that, the most obvious and direct possibility is that the
flame sensor is bad. If you'd had this code, this behavior from the
beginning, that would be the logical place to start. But what's odd
is how it behaved very differently initially, unless that was something
to do with you having the safety switch open, how you were starting it,
etc.

[Danny D.]

trader_4 wrote, on Tue, 23 Dec 2014 04:44:15 -0800:

> Ok, so now the question that might shed some light on what's going on
> is, what changed that allowed the furnace to get this far? Previously,
> it would come up with a flashing LED trouble indication as soon as power
> was put on, without firing at all. Now, it's firing, then shutting down
> because it thinks it hasn't lit.

I agree with you.

The manual says:
"NOTE: If the polarity is not correct, the STATUS LED on the
control center will flash rapidly and prevent the furnace from
heating. The control system also requires an earth ground for
proper operation of the control and flame sensing."

So, *both* the old and new LED indications point to a suspected
lack of "earth" ground (among other things).

Plus, the constant flashing stopped just about when I started testing
the power connections (although, I didn't *change* anything). I
wiggled everything. But I left the wiring as it was before.

Yet, suddenly, it stopped flashing constantly, and, instead, the
error migrated from a power problem to short cycling (which now
implicates either the flame sensor or the flame sensor control
circuit).

Yet, the flame sensor has only one wire, so, ground is clearly
the case.

> I think that may be relevant, because initially you had continous LED
> flashes that the chart says corresponds to reversed polarity. While the
> polarity isn't reveresed, I wonder if it will also give that code if the
> ground is missing? I ask that because the flame sensor is single wire
> and depends on a ground path back to the controller board. Is it
> possible there is a bad ground connection between the controller board
> and the furnace metal?

I'm thinking the same thing. A bad ground could cause the flame proving
electrode not to have its requisite 5 microamps to 6 microamps. In the
schematic, there are two "Note #5" comments, each next to the "GV" which
is the gas valve

Note #5 says:
"5. This wire must be connected to furnace sheetmetal for control
to detect flame."
https://www.flickr.com/photos/98287134@N02/15460746143/

I'll need to check that, remove it, sand it, clean it, & re-test.

I suspect ground is critical for the flame-sensing circuit, because
the DC current is only 5 or 6 microamperes, which is so low, I'm
going to have to figure out *how* to test it using coils of wire
wrapped around an ammeter.

> Other than that, the most obvious and direct possibility is that the
> flame sensor is bad. If you'd had this code, this behavior from the
> beginning, that would be the logical place to start. But what's odd is
> how it behaved very differently initially, unless that was something to
> do with you having the safety switch open, how you were starting it,
> etc.

Looking at the troubleshooting flow chart, it does now imply that
either the flame proving electrode is bad, or that the control to
that flame sensor is bad.
https://www.flickr.com/photos/98287134@N02/15894320489/

I agree with you:
1. Today I will clean all the grounds.
2. I will check that "Note #5" wire listed in the schematic.
3. I will re-clean the flame sensing electrode (just in case).
4. I will figure out how to measure 5 or 6 microamperes
(and it can be as low as half a microampere).

[Danny D.]

Danny D. wrote, on Tue, 23 Dec 2014 13:21:56 +0000:

> So, *both* the old and new LED indications point to a suspected lack of
> "earth" ground (among other things).

Found a service manual online, by the way:
http://manualslib.com/manual/22390/Bryant-Gas-Fired-Induced-Combustion-Furnaces-373lav.html

[Danny D.]

Danny D. wrote, on Tue, 23 Dec 2014 14:36:38 +0000:

> Found a service manual online, by the way:
> http://manualslib.com/manual/22390/Bryant-Gas-Fired-Induced-Combustion-Furnaces-373lav.html

Here's a better link to the service manual so you can
see the schematic and troubleshooting flowchart:
http://dms.hvacpartners.com/docs/1009/Public/00/SP04-62.pdf

[trader_4]

On Tuesday, December 23, 2014 9:37:04 AM UTC-5, Danny D. wrote:
> Danny D. wrote, on Tue, 23 Dec 2014 13:21:56 +0000:
>
> > So, *both* the old and new LED indications point to a suspected lack of
> > "earth" ground (among other things).
>

If the ground is affecting the flame sensor, then it't the ground path
from the metal cabinet/frame of the furnace to the control board. That's
where I'd be looking. There must be a ground wire that goes from the control
board to the frame and the frame is also grounded to the incoming AC.

[mako...@yahoo.com]

it is difficult to measure the 5 uA using a VOM.

I think you are on the right track.

Check all the grounds
This means the controller ground to the AC supply and ALSO the furnace chassis ground to the AC supply.

Check that the flame sensor insulator is clean so that there is no partial short to ground of the flame sensor output whick is a very small DC voltage or current realtive to funrace chassis ground.

Check that the flame sensor probe is not very dirty but I don't see how that would casue the original symptom, but culd casue the symptoms you have now.

Check that the flame sensor probe does not touch metal but is properly touching the flame.

The flame sensor probe acts as a tiny battery and the controller needs to sense that current. THe flame sensor current is relative to the furnce ground which needs to be connectd to the AC ground and to the controller ground. I guess also make sure the burner jets are also grounded to the chassis. The flame is grounded to the burner jets actually.

Mark

[Danny D.]

Looking up videos on troubleshooting a Bryant 373LAV flame sensor,
these guys clean it with a brand new five-dollar bill:
https://www.youtube.com/watch?feature=player_detailpage&v=tYwR9qL4lnk#t=130

This looks like a similar furnace to mine, with a similar issue,
and this guy does not recommend cleaning the flame sensor:
https://www.youtube.com/watch?feature=player_detailpage&v=iDnkdKsZhc0#t=366

After replacing the flame sensor, he shows the whole cycle:
https://www.youtube.com/watch?feature=player_detailpage&v=iDnkdKsZhc0#t=950

These guys use #0000 fine steel wool to clean the flame sensor:
https://www.youtube.com/watch?feature=player_detailpage&v=R7AKPgBB_R4#t=344
https://www.youtube.com/watch?feature=player_detailpage&v=jCqlGfZv8Es#t=59

All say not to touch the sensor with fingers, which I didn't
know when I first had cleaned it.

But, interestingly, *all* (of those) simply clean or replace the flame sensor
without *any* of them testing it for the 5 or 6 uamps of control current.
(I'll google separately for videos *testing* the flame sensor circuit
but this is already long.)

Normally, I test things before replacing them, but, none of the
technicians in the youtube videos I've found bothered to test it
before replacing it.

Even so, I might buy a spare flame sensor and igniter, and keep
it next to the furnace. Any suggestions as to good suppliers?

[mako...@yahoo.com]

>
> Here's a better link to the service manual so you can
> see the schematic and troubleshooting flowchart:
> http://dms.hvacpartners.com/docs/1009/Public/00/SP04-62.pdf

good..

see Fig 12.
Note #5 in the lower right corner.

This wire must be connected to furnace sheetmetal for the flamesensor to work.

THe note is for the return wire of the gas valve.

I'm not sure what they mean exaclty, but something there needs to get to furnace sheetmetal ground for the flame senor to work.

Mark

[Danny D.]

trader_4 wrote, on Tue, 23 Dec 2014 06:56:45 -0800:

> If the ground is affecting the flame sensor, then it't the ground path
> from the metal cabinet/frame of the furnace to the control board. That's
> where I'd be looking. There must be a ground wire that goes from the control
> board to the frame and the frame is also grounded to the incoming AC.

That's a good point in that the *control board* needs to be grounded,
as well, especially, since the *only* DC I can find is in the flame
sensor circuit.

Right now I'm looking up how to test the handful of microamps that
the flame sensor circuit needs.

I'm not sure how it works yet. I suspect the heat lowers the resistance
which then increases the current past a trip point, so, if that's the
case, I will try to measure that increased current when I figure out
how to measure the current.

[Danny D.]

makolber wrote, on Tue, 23 Dec 2014 07:05:32 -0800:

> The flame sensor probe acts as a tiny battery and the

> controller needs to sense that current. The flame sensor

> current is relative to the furnce ground which needs to
> be connectd to the AC ground and to the controller ground.

You're the first person to describe *how* the flame sensor
works, so, I appreciate that input, as the first step of
measuring something is knowing how it works.

I had suspected that the DC current through the flame sensor
changes with heat, such that the controller senses that change.

In the same vein, that's the same as saying the resistance
changes, such that the voltage drop across the flame sensor
and ground changes (which, I think, is your battery analogy).

I guess I could remove the flame sensor and put a bunsen
burner on it and measure the resistance change, but, right
now I'm looking up for how to test the current at such low
microamperes, when my Fluke 75 only has a 300ma scale.

I do have a cheap Radio-Shack emergency open-jaw ammeter in
my car trunk, so, I'll dig that up, but, I doubt it's
sensitive enough to go down to a microampere.

> I guess also make sure the burner jets are also grounded
> to the chassis. The flame is grounded to the burner
> jets actually.

The flame is grounded? (I don't understand that statement.)

[Danny D.]

makolber wrote, on Tue, 23 Dec 2014 07:05:32 -0800:

> it is difficult to measure the 5 uA using a VOM.

This guy tests the flame sensor in situ with an ammeter:
https://www.youtube.com/watch?v=OsIkK3AH1p4

The current for a good flame sensor starts at 0ua with no flame,
and then, with flame the ammeter reads 4ua.
https://www.youtube.com/watch?feature=player_detailpage&v=OsIkK3AH1p4#t=132

He mentions that a dirty flame sensor will read lower
current, so, now I know at least which direction the
thing goes.

a. There is no current when the sensor is cold.
b. There is low current when the sensor is dirty.
c. There is a handful of microamps when it's hot.

This guy removes the flame sensor and checks continuity
all along the stainless steel rod, using a technique
I have never seen before for a metal (conductive) rod:
https://www.youtube.com/watch?feature=player_detailpage&v=d6mnKXZLzzs#t=18

Here they hook up a Fieldpiece HS36 ammeter into the flame
sensor in series,
https://www.youtube.com/watch?feature=player_detailpage&v=OcxQRBbZvpg#t=365

They had a reading of 0ua when cold, 2ua when dirty, and 3ua
when cleaned. The difference between not working and working was
only 1ua, so, a bad ground would certainly affect microamps!

[trader_4]

AFAIK, it's a thermocouple, similar to what you'd have in a water heater.

You can probably buy a new one for not too much, might be easier than
trying to measure what u have.

[Pat]

On Tue, 23 Dec 2014 15:23:20 +0000 (UTC), "Danny D."
<dannyd...@gmail.com> wrote:

>makolber wrote, on Tue, 23 Dec 2014 07:05:32 -0800:
>
>> The flame sensor probe acts as a tiny battery and the
>> controller needs to sense that current. The flame sensor
>> current is relative to the furnce ground which needs to
>> be connectd to the AC ground and to the controller ground.
>
>You're the first person to describe *how* the flame sensor
>works, so, I appreciate that input, as the first step of
>measuring something is knowing how it works.
>
>I had suspected that the DC current through the flame sensor
>changes with heat, such that the controller senses that change.
>
>In the same vein, that's the same as saying the resistance
>changes, such that the voltage drop across the flame sensor
>and ground changes (which, I think, is your battery analogy).
>
>I guess I could remove the flame sensor and put a bunsen
>burner on it and measure the resistance change, but, right
>now I'm looking up for how to test the current at such low
>microamperes, when my Fluke 75 only has a 300ma scale.
>

Danny,
I don't think you fully understood his battery analogy. It really
generates voltage. Google thermocouple. If you put it in a bunsen
burner, use your Fluke on its DC voltage range and measure the voltage
to see if it is good. (It is also possible you are correct and the
device is a variable resistor that changes with heat, but
thermocouples are very common in gas heating appliances).

Pat

[Tony Hwang]

Hi,
I use O'scope to check flame sensor. If that is the problem, I'd just
replace it. If furnace fired and soon after it quits probably sensor
did not sense the flame. Isn't there a test point on the board when
temporarily grounded it will go thru logic steps of the operation.
I believe all Carrier board has it and Bryant is Carrier 2nd tier
product. Control board is quite common amongst brands. My cabin Trane
furnace has Carrier equivalent board in there. Furnace operation is just
a simple one line yes/no logic flow.

[Scott Lurndal]

APED Appliance Parts on W San Carlos street in San Jose has igniters, flame sensors
and control boards for most furnaces. I've been happy with my purchases
from them.

[Danny D.]

Scott Lurndal wrote, on Tue, 23 Dec 2014 16:49:18 +0000:

> APED Appliance Parts on W San Carlos street in San Jose has igniters, flame sensors
> and control boards for most furnaces. I've been happy with my purchases
> from them.

Hi Scott,

Thanks for that tip, as they're very close.
They're at 2280 Stevens Creek Boulevard, San Jose, CA 95128.

I called them at 408-977-0404, but, maybe they're on vacation
as they didn't pick up the phone (9-6M-F, 9-3 Sat) so I will
call again later.

I think, no matter what, I'll get a price on the flame sensor
and the control board, since they're the two implicated parts
at the moment (other than ground itself).

[Danny D.]

Tony Hwang wrote, on Tue, 23 Dec 2014 09:09:33 -0700:

> I use O'scope to check flame sensor.

I always wanted an oscilloscope; but I don't have one. :(

> If that is the problem, I'd just replace it.

Wouldn't you know it, but none of the service manuals have the
part numbers. I called Bryant and they said that both Bryant
and Payne use the same part numbers, but they didn't have a parts
list at their 800-428-4326x3 phone number.

They gave me four dealers to call, and all had messages, so,
I left a message with all four, hoping they'll get back to me
on the part number for the flame sensor and control board.

> If furnace fired and soon after it quits probably sensor
> did not sense the flame.

I agree.
The current conditions are classic for when the flame sensor
does not sense the flame (based on all that I've learned yesterday).

> Isn't there a test point on the board when temporarily grounded
> it will go thru logic steps of the operation.

Yes. But ...

The test is confusing (to me) as to what the correct procedure is.
Here's the test, on the bottom of page 10, of this manual:
http://dms.hvacpartners.com/docs/1009/Public/00/SP04-62.pdf

Here's what that test "says":

"To initiate the component test sequence,shut OFF the room
thermostat or disconnect the "R" thermostat lead. Briefly
short the TEST terminal to the ’Com 24V’ terminal. Status
LED will flash code and then turn ON the inducer motor.
The inducer motor will run for the entire component test.
The hot surface ignitor, blower motor-heat speed, and blower
motor-cool speed will be turned ON for 10-15 seconds each."

It's not clear which "R" needs to be disconnected, as there
is are two "R" wires at the thermostat, and one "R" wire at
the control board. I disconnected both.

Then I attached an orange wire to the "COM" terminal and
briefly touched the "TEST" spade on the control board.

Nothing happened.

I then turned on the power, and nothing happened when I did that.
I then turned on the power and held down the door switch, and,
this time "something" happened - but the results were confusing.

First the inducer motor went on (as expected), and then the
igniter lit brightly (as expected) and then nothing was visibly
happening until the inducer went off, about a minute or so
thereafter.

OK. I "think" I ran the test. What did it do?
I don't know.

What did it tell me?
I don't even know what to look for.

> I believe all Carrier board has it and Bryant is Carrier 2nd tier
> product. Control board is quite common amongst brands. My cabin Trane
> furnace has Carrier equivalent board in there. Furnace operation is just
> a simple one line yes/no logic flow.

I called Bryant who said that Carrier and Payne and Bryant are all
owned by the same company, and that Payne & Bryant are parts
compatible.

[Stormin Mormon]

On 12/22/2014 8:40 PM, Danny D. wrote:
> Stormin Mormon wrote, on Mon, 22 Dec 2014 20:11:18 -0500:
>
>> With a new filter, and open vents, should be much improved air
>> flow. Lets see who spots the non sequitor.
>
> I'm not sure I understand ...
>
> non sequitor === an inference that does not follow from the premises;
> specifically : a fallacy resulting from a simple conversion of a
> universal affirmative proposition or from the transposition of a
> condition and its consequent.
> - a statement (as a response) that does not follow logically from or is
> not clearly related to anything previously said.
>

Sorry, I knew you'd not get it. I ought not wrote
that.

[Stormin Mormon]

On 12/23/2014 10:14 AM, Danny D. wrote:
> Normally, I test things before replacing them, but, none of the
> technicians in the youtube videos I've found bothered to test it
> before replacing it.
>
> Even so, I might buy a spare flame sensor and igniter, and keep
> it next to the furnace. Any suggestions as to good suppliers?
>

I'd mention a couple, but you need to be
in the trade to buy there.

[Tony Hwang]

Hi,
If you want to run test just set the 'stat to lowest setting so it won't
call for heat or cool interfering with the test. Just with a short piece
of wire jumper the TP and ground momentarily the test will start.
Regarding sensor only thing could be different would be connector. If
you get one with wrong connector cut the leads and use
connector from old one. I know same is the case with HSI(hot surface
ignitor) Never touch HSI with bare hand, finger oil will shorten it's
life, also it is quite brittle. And cover plate removed, don't forget to
cheat the interlock switch. If you want to reset every thing just turn
the power on/off otherwise it'll take hours B4 it comes out of lock down
mode. All my houses I built I used Carrier product so I am quite
familiar with it's design. I always keep a spare HSI. I once got caught
in one cold winter night with burnt out HSI. I have to light the furnace
with BBQ lighter whenever furnace came on all night. Two fire places
in the house were not enough to keep warm, LOL! Good luck.
NO white Christmas this year. Day time it is above freezing.

[Tony Hwang]

Hi,
One more thing.
If you indeed need board, it could be universal type with wiring adapter
harnesses and instruction sheet. Board is quite pricy,
I hope you don't need one.

[Scott Lurndal]

"Danny D." <dannyd...@gmail.com> writes:
>Tony Hwang wrote, on Tue, 23 Dec 2014 09:09:33 -0700:
>
>> I use O'scope to check flame sensor.
>
>I always wanted an oscilloscope; but I don't have one. :(

http://www.bitscope.com/product/BS05/

[Oren]

On Tue, 23 Dec 2014 14:48:27 -0500, Stormin Mormon
<cayo...@hotmail.com> wrote:

> Any suggestions as to good suppliers?
>>
>
>I'd mention a couple, but you need to be
>in the trade to buy there.

Easy to get around. I bought a "trade" restricted part from Grainger.
They asked and I told them I was from the "government". They had no
account for the agency. Instead, this was a government cash.

They sold me the part UNDER the Forestry Department account. I had
the electrical supervisor at work have it installed by a convict
prisoner :)

Cash money talks!

[mako...@yahoo.com]

Ok,the flame sensor is just a wire. It does not change resistance with heat. Also the flame sensor has only 1 connection and as you shoild know, a complete circuit needs 2. The circuit is completed THROUGH THE FLAME to the metal burner. And the current does not come from the controller. The flame actually generates the current. The controller senses therescense of thos small current. So the flame is a small battery where the neg terminal is the metal burner and the positive terminal is the probe in the flame. The current is very small and i would not try to measure it unless you have the right kind of meter and know what to do.

Also the flame sensor in NOT like the thermocoouples which have two wires and generate current inthe two wires when heated. The flame sensor is different.

The flowing hot gas from the burner tothe probe creates a small current.

I donT know how important it is for the probe itself to be clean, but the insulator that holds the probe needs to be clean or else the small current willleak directly back to the grounded metal ans not make it to the controller.



Mark

[mako...@yahoo.com]

Ok, im a little wrong.
The flame senor works by rectification. The controller applies a small AC voltage and the flame lets the current flow in one direction only in effect creating a small DC current. The battery analogy is not exactly right.
Goggle flame rectification sensor.

Mark

[Danny D.]

Stormin Mormon wrote, on Tue, 23 Dec 2014 14:45:50 -0500:

> Sorry, I knew you'd not get it. I ought not wrote that.

No problem. I had guessed that you might have been alluding to
a situation where a conclusion would be reached without the
scientific logic behind that conclusion.

While a *lot* of people just throw parts at a problem, and
even more make inferences that have no basis in fact, I
"try" to make logical inferences, and I try to test the fact.

I'm not always right, and, in fact, I'm often wrong; but in
the end, the item gets fixed, usually by fixing the right part.

In this case, I "may" have to throw parts at the problem,
because every test I "can" do on the flame sensor circuit
shows a good sensor, yet, clearly, the flame sensing circuit
is not working.

I contacted at least 5 distributors today, and only two
would sell a consumer parts. One had the flame sensor for
$20, the other for $18, but the $20 lady called first, so
I ordered over the phone. Since she didn't require an up-front
payment, I presume she has ordered it by now, so, I'll buy it
from her anyway.

She had the control board for $450, while the other guy had it
for $250, so, that's a bigger difference. I spent a few hours
(literally) on my side, in the crawlspace, staring at that
darn furnace, reading the three PDFs, staring at that darn thing
some more, and, like an idiot, turning it on over and over and
over again (even disassembling and reassembling the burners).

In the end, I gave up on debugging further.
a) I can't definitively test the flame sensor (I can't even figure
out yet how it works)
b) It's either the flame sensor or the motherboard, and,
c) If it's a ground, I can't find it.

https://c4.staticflickr.com/8/7540/16090369211_097fc30d88_c.jpg

[Danny D.]

Stormin Mormon wrote, on Tue, 23 Dec 2014 14:48:27 -0500:

> I'd mention a couple, but you need to be in the trade to buy there.

I called a few today.

My hastily written notes are below, but I may have mixed a bit up
as almost all had to call me back so I invariably didn't have my
paperwork with me when they called back, so, it was hard keeping
them straight since they all sounded the same.

Slakey Brothers 1480 Nicora Avenue, San Jose
(sells only to contractors).

Appliance Parts, Bob 408-265-5030, San Jose
(sells to humans, $18 flame sensor, $250 control board)

APED Appliance, San Jose 408-977-0404
(sells only to contractors)

Residential Heating and AC 888-818-6374, Campbell
(sells to humans, $20 flame sensor, $450 control board)

Air Care Heating & Cooling, San Jose 408-513-3089
(doesn't sell parts, $80 for a service call)

Coldcraft 888-918-8662
(doesn't sell parts, $139 for a service call)