Compressor type

[David Friedman]

My understanding is that Hallowell switched compressors at some point,
Note that the service bulletin states serial numbers past which to
start worrying about the contactors. As per a previous post - I am
days away from releasing a simple and dramatically improved fix for
the Acadia's but my confidence will be increased if I can track this
down.

Do any of you owners or HVAC guys have access to units with the
original compressor. I believe that when he switched - he went to a
dual contactor starting circuit from Bristol with a fatal flaw and the
shit hit the fan.

Please inspect any units with the earlier serial numbers and let me
know what compressor was used. THIS IS CRITICAL

---------------------------------------
Product Service Bulletin PSB10-02
Date: March 29th. 2011
To: All Hallowell International Distributors, Hallowell Dealers.
Hallowell Engineering.
Hallowell Manufacturing, Hallowell Procurement, and HalloweII
Logistics.
From: Duane A. Hallowell, President / CEO
Subject Recommended Upgrade
Importance: High
Problem: Primary compressor definite purpose contactor upgrade.
Acadia024 serial # starting with 24A2
Acadia036 serial # starting with 36A2 and 36A2P
Acadia048 serial # starling with 48A2 and 48A2P
This is a recommended upgrade affecting all Acadia Model Heat Pumps.
The GE definite
purpose contactors model CR453CC2HAA used in the starting circuit of
all Acadia T81J
primary compressors can exhibit a high contact resistance or
inconsistent “open" readings
on the L2 pole of the DP contactor. The high resistance or
potentially
"open” circuits can
cause inaccurate responses of the potential relays and associated
capacitors. This erratic
behavior can cause an overheating event in the primary compressors
motor causing
electrical motor failure. The Bristol T81J compressor is more
susceptible to high resistance
due to its recommended dual relay starting circuit.


Action: Replace the primary T8IJ compressor contactors, relays, and
capacitors:


The GE contactors should be replaced wtth Siemens brand 40 amp
contactors for the
Primary Compressors 1 & 2 Cylinder for this upgrade. Additionally, we
are recommending
that the primary 1 & 2 cylinder potential relays be replaced due to
possible premature wear
to the relays armature. The primary 1 & 2 start and run capacitors
should be tested and
inspected for proper microfarad readings and to be free of defect.
Please inspect all wiring
and electrical connection points. Please use only Hallowell specified
equipment for this
upgrade. Contactors, relays and capacitors can be purchased through
your local Hallowell
Distributor.


Duane A Hallowell
President / CEO

[Brian Goates]

My SN is # 48A2019625 so falls in line with this bulletin.

 

I changed out my contactors and my unit still lives.

 

My compressors has two labels....Benchmark Compressor which comes up Bristol and it has a TS Technology label on it and this is what I found about it when I googled TS tech:

 

TS Technology

Efficient, optimum performance with less expense. That's TS Technology. A unique "twin-single" piston system that allows for two-speed operation provides a compressor capable of running longer and at a lower capacity. This means optimum heat pump performance in both heating and cooling modes with just one compressor doing the job of two.

[David Friedman]

Brian

 

I have very strong technical evidence that you will run into problems.  If you  look at the schematic for your unit - there are two double pole contactors used.  The failing contact is the one that closes the circuit (and breaks the circuit later) for the potential relays.  Different potential relays are used as the motor is spun in two different directions.

 

I strongly believe that Hallowell originally used a different compressor from the ts line (there are 54 ts compressors)  The older compressor runs at a slightly reduced efficiency and used as its starting circuit the 2 wire kit from kickstart - KSTS234. 

When he switched to the TS81 in our untits - Bristol told him to use the dual contactor - dual relay circuit shown in your wiring diagram.  This circuit has a fatal flaw although I can't get Bristol to admit complicity.  Namely the second contact (the ones that fail) are used to power the very low current - highly inductive potential relays - and then this contact arcs when compressor is turned off.  The Seiman's will arc and fail also.

 

I feel strongly that placing a 10K power resistor across the potential relays of sufficient wattage to withstand the s to c or r to c voltage - will eliminate the arc and that is one possible solution.  This should be tested - and you are in a position to do this.  Simply push in the cyl-1 contactor and let the compressor run for a while,  and then drop it out while observing if the contact  arcs on the contact that breaks the common to the potential relay.  Placing a 10K power resistor across this relay will (I think) stop the arcing and prolong life. (when an inductive load is opened the store denergy in the inductor tries to keep flowing and can cause thousands of volts and an arc.  If this is shunted by 10K (about the same resistance as the relay coil) then the kick will be limited to a few hundred volts and not arc.

 

You will be doing the field a great service if you could do this test.

 

Another alternative mentioned in discussions with Bristol is to replace the entire dual relay starting system with a two wire KSTS-324 kit (for the four ton).  This uses a different type of potential relay which is wired directly across the run cap and thus protected by the motor itself when shut off.

 

The advantage of this fix is that the KSTS324 included a bleeder resistor across the start cap.  Bristol demands that this be done - but Hallowell (shitheads they were) left this component off)

 

The issue is that when the potential relay in your system fires to disconnect the start cap - with no bleed resister - the start cap retains its voltage which might be as much as 400 volts.  Later when the motor is turned off and the potential relay drops out - there is a dead short as the start cap discharges into the run capacitor.  This tends to weld the power contact.

 

So.  Repeating.  I think from my professinal experience (MSEE) the low powered side of the dual contactor - despite being a 35 amp contact breaking only milliamps - will arc and fail.  Also the lack of a bleed resistor will cause the high powered side to fail. 

 

I plan to replace the whole mess with a KSTS 324.  Note:

 

Look up the bristolcompressor.com web page and type in ts to get the full ts family.

 

In the 89 series there are both smaller and larger units than our T81 - and the slightly smaller unit uses a KSTS with a smaller start cap as needed for that motor - and the slightly larger unit uses the same start cap as our motor - and uses the KSTS324 to start.  Given that they used KSTS324 to start an even bigger motor - it should do fine for ours and since it uses the right start cap it should work fine.

 

I this this is the way to go.  Stay in touch.

 

Dave Friedman

[cpeters99]

This is a repost but what do you think about what this Bristol
engineer told me:

From: Larry Pippin <larry.pip...@bristolcompressors.com>
Subject: RE: Contact Requested / Quality Assurance
To: "Chris Peters" <cpeters...@yahoo.com>
Date: Thursday, February 17, 2011, 10:29 AM


Chris,

Would windings damaged by a failed start relay cause the compressor to
be noisy once it cools down? Not a mechanical noise.

Anyway, I am wondering if you may have any insight or suggestions
particular to the Hallowell system. I would like to make this last,
if possible. ANSWER: If it were my system I would eliminate the hard
start kit by equalizing the compressor before each start up. You would
need to cycle the compressor off until the compressor or compressors
are equalized. One way of doing this is install a check valve in the
discharge line of each compressor (do not use a ball check valve us a
magnetic check valve by Henry Technologies part number suggested
MS887) and attach a cap tube below the check valve and attached the
other end of the cap tube to the suction line of the compressor. This
will allow the high pressure below the check valve to leak back into
the low side of the compressor equalizing only the compressor leaving
the system at normal pressures. The cap tube size is approximately 3
foot long and with .026 inside diameter of the cap tube. If you do
this
correctly your system should last as long as a single speed
compressor 15 to 20 years or longer. During the off time waiting on
the compressor to equalize in 3 minutes approximately the blower will
be blowing unless you have it to shut off during the equalizing time.
If you use a small solenoid in the place of the cap tube then you
could eliminate the run time during the equalizing time by equalizing
very quickly. You will need to us a PTCR starter light start assist to
make sure the compressor start each and every time mainly during low
speed starting. You can go to our Bulletin 110 that is on our website
and you will find information on the PTCR starter. You can go to our
website and pull up the specification sheet on each of your compressor
and it will give the recommended PTCR for each of your compressors.
The C9 most likely will be the PTCR for the larger compressor.

Note: The leakage through the cap tube during normal operation should
not be of any concern on efficiency and capacity due to the leakage
being so small.




Larry Pippin
Senior Field Service Engineer
Bristol Compressors
15185 Industrial Park Road, Bristol, VA 24202
276-645-2458 office, 276-645-7561 fax
Larry.pip...@bristolcompressors.com
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[Brian Goates]

Dave, I am Joe the homeowner, fairly handy and resourceful but hardly a MSEE!

 

If you can tell me how to test this in layman terms, I will do it. It sounds as if you want me to observe arcing in the contactors? I seem to recall these new Siemens units are enclosed (can't see the contacts) unlike the GE's that I replaced.

 

I just need a graphical explanation, part number for the 10K resistor (or just buy any one from an electronics store?), a clear explanation of where/how to wire this resistor or I may have to get an electrician up here. Sounds like this is wired between the two contactors or?

 

 

Please tell me what to look for or I can send you a pic of the guts of the beast and you can directt me including the where to source the KSTS 324, how difficult to replace. I do see the reference in the 89 series that you mention. If not too difficult or expensive I'll just go that route (the 324).

 

Thanks ! Brian

[David Friedman]

Chris,

 

I think that Pippin (a plumber who doesn't know an olm from a volt) is correct in that equalized start is easier on the motor - but there is no way I think it is practical for we who have installed equipkent.  Also I don't know if there are any timing restrictions that would not be assured in tHe Hallowell logic.

 

When I make my HVAC presentation on tuessday - I will raise the issue.

 

----------------------------------------------------

 

But Chris  - remember that what Bristol is trying to do is get out from their original design recomendation to Hallowell to use hard start - albeit with the potential relay dual relay - dual contactor scheme that I say is flawed.

 

Pippin had trouble understanding my explanation of why their circuit fails - and tried to talk me into replumbing which I could not do or consider.

 

---------------------------

 

What is the state of your system now?  Did you replace the contactors or is the system as is.  If you didn't replace contactors yet - you could do the test I suggested - but we shouldget together on the phone and discuss.

 

978-505-5581    dafr...@gmail.com

[David Friedman]

Thanks.

 

I havn't recieved the Sieman's contactors yet and didn't realize that they are closed.  This is probably what led Hallowell to think they would last longer in the low powered use - but I think him wrong.

 

Given that they are enclosed - the only way to see arcing is to have an oscilliscope inplace - which neither of us have.

 

I am making a presentation to a group of HVAC people this tuesday - and perhap I can get one of them to help me with the test or perhaps we will just decide to go the replacement "kickstart" route.

 

For now - I would advise carefully monitoring your system as it uses stage one in AC to make sure it doesn't fail. 

 

------------------------

 

If I get a thumbs up from my HVAC contacts tuesday - I plan to press F.W. Webb to authorize me to write up the fix I propose and then it will be in a wire by wire with pictures form.

 

---------------------------------

 

By the way - Pippin is the Bristol guy who I worked with (and his supervisor)  He is a plumber and doesn't knww an ohm from a coulomb!

 

His first take was to not even understand what I was saying about the arcing.  He then said perhaps - and then suggested swapping out the dual relay circuit for the KSTS parts.

 

When he realized that I was pressing him for some solid answers he and his boss got scared and reverted to a proposal to replumb the systems to use equalized start in which the compressor doesn't have to work as hard at start (totally not practical!) and pointed back to the spec sheets which told Hallowell to use the circuit I know will fail.  I think they are liable!

[Chris Peters]

I had a contactor fail last summer that was replaced with a Seimans after it started chattering.  The caps and starter relays were replaced with the bulletin the year before.  My primary compressor windings failed in feb.  I probably got the last warranty compressor from hallowell about 2 weeks before they disappeared.  They also sent the potential relays and contactors (Seimans).  they're sitting in the basement waiting to decide what to do.  I'm not a plumber but I know basic ac (I was a master GM automotive tech for 20 years) and how to braze copper.  I don't see why it would be too hard to put a bleed line in as well as a solonoid controlled by a delay timer after shutdown.  It sounds like a good idea, to make sure the pressures are equalied before start up.  I now make programmable logic controllers and io boards for the gaming industry, if I could get a failed board (or even just the eprom chip) I can read the eprom.  Their control is not that complex, there are only 7 or 8 outputs and 3 or 4 inputs besides the tstat and air handler.  Nothing is controlled to the milisecond, if you know what I mean.  The patent I posted before by Purdue describes a more complex system of control including pressure equilization with only a couple more inputs.  They also include an accumulator after the economizer.  This would be tough to do with what's there, burt the extra sensor for timing compressor delay after defrost (or other quick cycling times) would'nt be hard.  I get high speed controllers and IO board combinations (micro pc) for just over a hundred bucks.  Some of these have 10 inputs and 10 outputs, more than enough, and program in windows or whatever you like.  You could make it do whatever you want fairly easily.   I also use small touch screen panels to interface with the controllers.  You could have a touchscreen thermostat with complete diagnostics and sensor data and status display.  That's drifing off course.  I certainly am no hvac expert.  My understanding of a hard start kit is it is a last resort to try to milk a little more life out of a tired compressor, it is just blasting the current even harder to force the compressor to turn no matter what.   I would love to make my acadia last at least as long as the loan!  What do you think?  Chris. --- On Sat, 5/28/11, David Friedman <dafr...@gmail.com> wrote:

[cpeters99]

Sorry, I'm sure I don't know what I'm talking about, I certainly don't
want to upset anyone, so I'll just forget Pippins idea. I do have one
question though. If anyone has actually replaced a failed primary
compressor due to motor winding damage from a failed contactor, will I
need to worry about acd in my refrigerant system due to the overheated
windings. Mine was cooking for a few hours and was pretty hot. I
haven't opened the system yet.

On May 28, 8:55 pm, Chris Peters <cpeters...@yahoo.com> wrote:
> I had a contactor fail last summer that was replaced with a Seimans after it started chattering.  The caps and starter relays were replaced with the bulletin the year before.  My primary compressor windings failed in feb.  I probably got the last warranty compressor from hallowell about 2 weeks before they disappeared.  They also sent the potential relays and contactors (Seimans).  they're sitting in the basement waiting to decide what to do.  I'm not a plumber but I know basic ac (I was a master GM automotive tech for 20 years) and how to braze copper.  I don't see why it would be too hard to put a bleed line in as well as a solonoid controlled by a delay timer after shutdown.  It sounds like a good idea, to make sure the pressures are equalied before start up.  I now make programmable logic controllers and io boards for the gaming industry, if I could get a failed board (or even just the eprom chip) I can read the eprom.  Their control is
>  not that complex, there are only 7 or 8 outputs and 3 or 4 inputs besides the tstat and air handler.  Nothing is controlled to the milisecond, if you know what I mean.  The patent I posted before by Purdue describes a more complex system of control including pressure equilization with only a couple more inputs.  They also include an accumulator after the economizer.  This would be tough to do with what's there, burt the extra sensor for timing compressor delay after defrost (or other quick cycling times) would'nt be hard.  I get high speed controllers and IO board combinations (micro pc) for just over a hundred bucks.  Some of these have 10 inputs and 10 outputs, more than enough, and program in windows or whatever you like.  You could make it do whatever you want fairly easily.   I also use small touch screen panels to interface with the controllers.  You could have a touchscreen thermostat with complete diagnostics and sensor data and status
>  display.  That's drifing off course.  I certainly am no hvac expert.  My understanding of a hard start kit is it is a last resort to try to milk a little more life out of a tired compressor, it is just blasting the current even harder to force the compressor to turn no matter what.   I would love to make my acadia last at least as long as the loan!  What do you think?  Chris.
>

> --- On Sat, 5/28/11, David Friedman <dafrie...@gmail.com> wrote:

>
> From: David Friedman <dafrie...@gmail.com>
> Subject: Re: Compressor type
> To: hallowel...@googlegroups.com
> Date: Saturday, May 28, 2011, 1:45 PM
>
> Chris,
>  
> I think that Pippin (a plumber who doesn't know an olm from a volt) is correct in that equalized start is easier on the motor - but there is no way I think it is practical for we who have installed equipkent.  Also I don't know if there are any timing restrictions that would not be assured in tHe Hallowell logic.
>  
> When I make my HVAC presentation on tuessday - I will raise the issue.
>  
> ----------------------------------------------------
>  
> But Chris  - remember that what Bristol is trying to do is get out from their original design recomendation to Hallowell to use hard start - albeit with the potential relay dual relay - dual contactor scheme that I say is flawed.
>  
> Pippin had trouble understanding my explanation of why their circuit fails - and tried to talk me into replumbing which I could not do or consider.
>  
> ---------------------------
>  
> What is the state of your system now?  Did you replace the contactors or is the system as is.  If you didn't replace contactors yet - you could do the test I suggested - but we shouldget together on the phone and discuss.
>  

> 978-505-5581    dafrie...@gmail.com

> > President / CEO- Hide quoted text -
>
> - Show quoted text -

[David Friedman]

Chris

 

We are in the same boat and your suggestion to consider redesigning the Acadia to not have the compressor "hard start" is not at all crazy.  but it is a bit compex and my expertise is electrical - not HVAC plumbing - so it seems complex.  If programmable controllers are needed fo rany delays or controls needed - your expertise could be great - but I am not cnvinced that equalized compression - as nice as that is - is needed. 

 

Specifically it misses the boat with respect to the sequence of failures in the Acadia as I have analyzed and understood them.

 

My research shows that the original Acadia ACHP and the first few hundred Acadia's used the T89 compressor from Bristol which was speced to use "kickstart' components to start the motor.  The "kickstart" uses the start capacitor specified on the spec sheet which determines the initial starting current - and senses the potential between r to s or s to r in the second stage - to then disconnects the start cap.  These systems worked fine!

 

In an attempt to get more effieciency and based on pressure from Bristol - Hallowell switched to the T81 compressor line - which for reasons not currently understood - was qualified to use potential relays to control the start cap disconnect rather than the simpler KSTS "kickstart" parts.  Such a scheme kicks the motor just as hard as using "kickstart" -- that term is just a trade name for starter systems that sense the voltage from  r to s rather than from r to t or s to t. (2 wire rather than 3 wire starters)  During starting - while the start cap is connected - they operate identically.  And if the sensing relay doesn't pick - they fry the motor just as would be the case with the failed contacts.  the differance is simplicity with only one sensing device from r to s and no contact to connect and then disconnect the potential relay --- which is what failed in the Acadia's.

 

Your Acadia (and mine) used the dual relay -dual contactor scheme shown on your Acadia schematic - which disconnects the start cap when the r to c or s to c voltage is at rated voltage.  However - that scheme has a fatal flaw - not understood apparently by either Bristol or Acadia - based on the simple fact that it is bad electrical practice to disconnect a relay (the potential relays) with a contact -- and this is the failure that occurred.  The low current second contact  on each of the power contactors used to start the ts in either direction arced when disconnected and eventually went high resistance and failed to disconnect the start cap - and then blew the compressor. 

 

Acadia - in my opinion - misdiagnosed this failure simply assuming they had bum contacors and switched to Sieman's.  In my opinion these will fail and did fail for the same reason.  One can easily test for high resistance across the contacts'

 

My proposal - based on its ability to eliminate that fatal flaw and also cure the failure of Acadia to put a bleed resistance across the start cap which causes it to store voltage and to weld sometimes when the potential relay drops out is to use the KSTS 2 wire start device using the part number equaling the start cap value specified for our compressors.  This system does not have the contact arcing problem and also included a bleed resistance across teh stat cap which Bristol clearly specified - and Hallowell ignored what is an obvious requirement.

 

Finally - I wouldn't worry about secondary damage caused by the motor buring up  since there is no real connection between the motor and the refrigerant.

 

Given that you have a free compressor - I would rewire the system to use the KSTS kickstart combined rely/start cap - removing the now in place start cap and wiring the new part across the run cap terminals,  and have a HVAC tech use Hallowell instructions for replacing your primary compressor. 

 

I see no reason to think that you shouldn't be able to get your sytem back on the air.

 

David

[David Friedman]

Chris

 

(what is your e_mail so we can continue directly)

 

Chris

 

I have been maintaining that GE to Seiman's replacement was bullshit - and real problem was arcing of an unprotected relay contact.

 

You replaced the GE contactors and then had failures. the state of the contactors on your system is a fantastic piece of info.   If the Seiman's cocntactors failed causing your compressor failure - we have really nailed what is the basic cause of the problems!!!

 

SO:

 

Go to your system.  Shut down the power so you wont kill yourself.

 

Find the primary one and primary two contactors.  Carefully with a low ohmage scale meter - measure the contact resistance when the contactors are pushed in to engage them manually.

 

The failure mechanism I suspect would show high resistance on the contacts which connect over to the 1-cyl and 2-cyl relay coils.

 

This causes the potential relay to not pick and keep running the motor with the start cap engaged and burns it up unless the internal Bristol disconnect saves the compressor.

 

Please go out to your junk unit and make this measurement.

 

David

 

 

On Sat, May 28, 2011 at 9:17 PM, cpeters99 <cpete...@yahoo.com> wrote:

[Chris Peters]

I will check this tomorrow.

--- On Sat, 5/28/11, David Friedman <dafr...@gmail.com> wrote:

[Chris Peters]

But I have bleed resistors on my start caps and did before the first contactor failure.

--- On Sat, 5/28/11, David Friedman <dafr...@gmail.com> wrote:

[Brian Goates]

David, looking around to try and figure out was entailed with a kick start upgrade and stumbled on this.

 

http://www.kickstartoem.com/faqs/contractors.html#3

[David Friedman]

Brian

I had found this - and then went back to Bristol specs and realized that T89 used these devices specially set up with start caps matching our needs.  For reasons unknown - they did not qualify the T81 (later compressor that Hallowell switched to mid line) and forced the Acadia to use the more complicated two relay two contactor hard start in our machines.

Bristol refused to take responsibility for contact failures - taking the same line as Hallowell that it was a contactor problem and suggesting Seiman's swapout.

I will stake my (retired) professional reputation as an MSEE with 12 patents - that both Bristol and Halloway were wrong and the dual contactor system is fatally flawed since the unpreoteted coil willarc when "dropped".

I am convinced that putting a 10 K 25 watt power R across the coils of the potential relays will solve the arcing.  Note that there has bee reports of continued failure with the Seiman's.

If I had an oscilliscope I would monitor the contact voltage when the contactor drops the potential relays and prove my case -- but I don't.

Since most of the units in the field have failed (open contacts) on the contact used to pick the potential relays which was how mine failed - and which will lead to compressor failure when start cap stays connected - I am more inclined to suggest that we rip out the dual relay/dual contactor solution and replace with appropriate KSTS devices which are still available since there are many t89 compressors in the field which were directed by Bristol to use the KSTS parts.  Note that there are both smaller and larger but very similar motors used in the t89 series - so I don;t see why they should not work,  and I got a mild endorsement from Bristol suggesting that direction. 

[Brian Goates]

Pondering all this, I have been running for 3 years this October. I was having issues (it was the thermostat) but Hallowell sent me these upgrades (see pics) in 09. I have been fine ever since. Any thing that catches your eye here?

 

So what is it that "wears out" after time? I had the upgraded GE contactors (in attached) installed in 09 then I just replaced them with the Siemens. They were relatively inexpensive and easy to swap out.

 

Left to my own means I would replace the contactors every 18 months. So you are saying we have a ticking and unpredictable timebomb with this flaw? What does "dropped" mean?

 

It sounds like the start cap upgrade if embraced by Bristol may make sense and is not that difficult? 

 

Is the 10 K 25 watt power R suggestion good insurance? Any risk to this? Can you detail how I do it?

 

Meanwhile we had snow last night (In Northern Nevada) and my Hallowell is humming (grinding !! -??) away.

 

Tks, Brian

[Chris Peters]

I have a tektronics scope, tell me what you want to know.

[Chris Peters]

David, would you be able to draw a schematic so I can understand how you would wire the kickstart to control both directions of rotation? --- On Sun, 5/29/11, Chris Peters <cpete...@yahoo.com> wrote:

[David Friedman]

Hallowell seems to have replaced both potential relays and the start and run caps involved with motor starting. that BM doesnot include the Seiman's replacement contactors for the GE's - but that must have been a different order.

 

 I see little risk in the resisters placed across the potential relay coils.  Those relays see at most 400 volts while the motor is running (either cyl-1 or cyl-2 will see voltage from r to c or s to c while motor runs causing the one connected to C via either the primary 1cyl or primary 2 cl contact which is closed. (only one of these power contactors closes to decide which motor direction) The power in the resistor would be V^2/R and comes out to about 16 watts so a 25 watt resistor should be fine. They will get hot and needs surface mounting.

 

The two 1-cyl or 2-cyl (look at your schematic) relays are 6K and 14.8K respectively.  The actual coil current is even less than the voltage divided by the resistance due to the AC impedance of the coil - but at most is 300/ by the respective coil resistance.  When the motor gets up to speed and the voltage is high enough across the cyl-1 or cyl-2 relay to cause it to open the starting cap is disconnected by the given relay.

 

BUT when the the compressor is turned off at the end of its cycle - the path through the high powered contact to the puny little relay coil is broken - and the current flowing at that instant has nowheres to go.  It tries to arc and sometimes does - causing carbon on the contactor.  Eventually the contact opens and then the 1-cyl or 2-cyl relay can't operate leaving the starting cap in place with the motor drawing 7 to 8 times as much current as its run current.  This pops the overload protect on the compressor - but as it keeps retrying the compressor eventually burns out.

I am trying to decide between the resistor fix for the contactor problem which should work but I don't have a test facility to try it out - and on my unit both contactors are now failed open and I can't even use it as a test bed until I get new parts) or to abandon the dual relay starting scheme in favor of a 2 wire kickstart wherin the KSTS relay coil is wired across the run cap - and internally to the KSTS connects a start cap to the run cap - until the relay operates.  Note that such a 2 wire scheme works in both directions - but the actual voltage at which the start cap is removed is the same in both motor directions whereas in the dual relay scheme the point of disconnect is lower for the cyl-1 than for the cyl-2. 

 

For reason's unknown - Bristol didn't specify the use of KSTS parts for the t81 line of compressors - but did so for the earlier t89 line.  Duane Hallowell started with the ACHP with the t-89 compressor and a KSTS 2 wire start kit - and those units are still running. 

 

I believe that the major cause for the later (most) Acadia's was the dual contactor failure mechanism I mentioned.

 

If someone could get an oscilliscope and monitor the voltage which appears at the point where the power relay contact meets (picks when enough voltage is present on the other side of the coil) the potential relay, I believe that when the compressor shuts down - you will see high voltage and hash  at that point characteristic of a contact which is arcing.  I think having a 10K power resistor across that relay coil will prevent this with no risk that I can think of.

 

This would leave us with a starting circuit totally authorized by Bristol (for what thats worth since the warrenty was voided by Hallowell mods).

 

My alternative solution of switching from two relays and two power contacts to a single 2 wire device of the correct start capacitance only has the value of simplicity - especially if the power contacts on the GE's or Seiman's are totally solid as they seem to be on my unit.

 

David

[David Friedman]

The BM you sent shows replacement of the potential relays, start cap, and run cap - but not the contactor.  Something is confused.

[blgo...@gmail.com]

There was another page with the GE contactors. I already changed them out for the Siemens so I did not send it. 

    

   --Sent from my iPhone--

[docwelby]

It is expected to be in the 90*s today in Chicago. My compressor
failed last month so I am without cool air. It had been replaced from
the original. Are there any compressor replacement options or should I
just bite the bullet and buy a new unit? I need to make a decision
SOOOON. Thanks to all of you posting!!!!

[David Friedman]

As I have been reporting - there was a gross Bristol specified design error with the dual relay starting circuit used to start the primary compressor.  Note that there have been virtually no booster compressor failures and that part is Hallowell's inovation.  The primary compressor setup is pure Bristol and Hallowell unfortunately didn't catch their design error.  He tried to respond to the failures by swapping from GE to Seiman's contactors - but that is a patch at best.

 

In the primary circuit,   when a single contact on the dual pole contactors fail open due to arcing from dropping an uprotected relay - the start cap doesn't pull and enourmous power pours thru the start cap blowing it, then the compessor if not stoppped soon enough.

 

When this happens - replacement of all of the starting components are needed - but in addition I have designed in (and am waiting for parts to install and check out carefully) the use of damping resistors across the 1-cyl and 2-cyl relays.  If I am right and I have 12 patents in EE,  an MSEE, and helep start  and ran engineering for a high tech company - Computervision,  adding two $2.5 parts will totally solve this horrible failure mechanism.

 

But - since many are already reporting "blown compressors".

 

Gabe Josephs who has installed 50 of these and stuck by his customers (I wish he was my service guy up here in Laconia NH) has found that even fried compressors may still work.

 

He has been ohming them to assure they are neither open or shorted,  and then replacing the starting components,  and often gets units going again.

 

 The only way to tell is to disconnect compressor leads - and ohm out the motor coils both R to S and S and  R to  C,  and all to ground.  I have attached a spec sheet that shows what these resistances should be.

 

Your mention of the "shunt resistor" must have been the mod to place a bleed resistor across the start cap. (not the resistors I am adding)  This is a good thing - but not the primary cause fo failure - which was the phenomenon I detected based on my own engineering background,

 

If the compressor is blown - replacement is probably marginal although - as amazing as this may sound - I am firmly convinced that given the latest rev of control board and temperature sensors which made orders of magnitude improvements in icing problems - and after the utterly simple fix to the starting circuit I designed this month which will make the contactors last and not induce the capastrophic power failures leading to compressor failures --- I think think an Acadia should run as long any  Heat Pump.

 

David Friedman

A homeowner not connected with the company in any way

[jptra...@gmail.com]

Jeez David,

I wish you were down in Marblehead. I have been following along the blog and feel like Im learning more about the system but unfortunately as a family doctor I dont have the time or the knowledge to mess around with the system. My HVAC guy, while I have great respect for him, isnt familiar enough with the system to support this either so I am abandoning my 4 ton unit for a conventional heat pump and will have to use my back up water coil off the boiler in the cold months. That being said, anyone who is interested in a 4 ton unit let me know and I can have the coolant drained. It needs to come up a flight of stairs to be removed and its freakin' heavy...

[Chris Papademetrious]

Retrofit road trip tour?