adding R134a to a 2002 Sienna

[Michael]

I have the exact same problem as this guy, and I'm wondering if the
solution is the same.

http://www.toyotafans.net/2004-sienna-rear-ac-unit-not-cold-t4400.htm

I've seen cans of R134a at the store, and I'm wondering how difficult
this is to do. What are the specs on the minimum pressure at the low-
side charging port? This doesn't seem to be specified in the Haynes
manual I've got.

I'm guessing I should get a can of R134a that has a pressure gauge, so
I'll know how much refrigerant I need to add... if any.

Also, where exactly is the low-side charging port? Again, the Haynes
manual isn't very clear about *where* it is.

Thanks,

Michael

[Michael]

I went over to Wal-Mart, and I noticed the cans with a pressure gauge
have a nice table printed on the can as to what the pressure should
be, depending on the ambient temperature. I also noticed they sold
cans without a pressure gauge (which were half the price as the ones
with a gauge). How on earth would you know when to stop, without a
gauge?!

I was about to buy a can with a gauge, then decided to do a little
more research before committing to a can. I have to go back there to
get a Father's Day gift anyway. =)

[hls]

"Michael" <mrda...@gmail.com> wrote in message
news:f95a3ab9-43a3-46ba...@nl1g2000pbc.googlegroups.com...

>I have the exact same problem as this guy, and I'm wondering if the
> solution is the same.
>

It might be, or it might not be. You will need to measure the pressures in
the rear
system and see what is going on. If you dont achieve the specified
pressures, then
you have either a lack of refrigerant OR you have a mechanical problem with
the
compressor, valves, etc.

If you know how to do it, you can buy a can of refrigerant with a pressure
gauge,
and you can attach it to the vacuum side of the compressor. Add
refrigerant
very slowly until your pressure measurement reaches the value mandated. (You
can find this on your can of refrigerant or you can find it from the data
for your
particular application)

If you have adequate cooling, then you guessed correctly.

The more certain way is to take this beast to a competent refrigeration
mechanic
and avoid the mystery.

[hachiroku]

Oh, you mean the "Blow up Cans"?

MAKE SURE YOU KNOW WHICH IS THE LOW SIDE BEFORE ATTACHNG THE CAN!!!!!!!!!!!!!!!!!!!!!!!!

I have also wrecked a compressor with this stuff.

[Michael]

I suppose. I think they're also called Suicide Cans? =)

> MAKE SURE YOU KNOW WHICH IS THE LOW SIDE BEFORE ATTACHNG THE CAN!!!!!!!!!!!!!!!!!!!!!!!!

I am guessing... just a guess... but... I think I want to avoid the
one that has a letter "H" on it.

Besides, I hear the fittings won't fit on the HIGH side.

> I have also wrecked a compressor with this stuff.

Oh that reminds me. Should I get Toyota-branded R134A? Synthetic?
Wal-Mart stuff? Car Quest?

How did you wreck a compressor anyway?

[uncle_vito]

>How did you wreck a compressor anyway?

You get overenergetic in your rate of adding R134a. It goes into the low
pressure side which is at the inlet to the compressor. You get liquid freon
in there and the compressor locks up and self destructs.

In answer to not having a pressure gauge, if lack of freon is the problem
then any additional will help. Just limit the addition to no more than two
cans. If the AC is not cooling at all, you are likely empty and two cans
will not overfill it.

You can also tell if you are sufficiently full by feeling the low pressure
line and seeing if it is cold or accumulating frost. If it is cold,, then
you have enough freon. Not totally full, but enough. So stop filling.

[Ralph Mowery]

"Michael" <mrda...@gmail.com> wrote in message

news:1d956ab8-6bee-416a...@ra8g2000pbc.googlegroups.com...

>How did you wreck a compressor anyway?

The Low side is usually the larger pipe.

The refrigerant will normally come out of the can as a gas if held vertical.
If tiped over or held upside down, liquid will come out. The liquid can get
into the compressor and break the valves or cause other mechanical damage.

This is one area where if you have no idea what you are doing, you can cause
lots of damage to the system.

If the car is a 2002 and you have a leak, it probably needs to be repaired.
I had a 1991 Camry for 17 years and never had any cooling problems.
It is a closed system and does not get used up or wear out. It has to leak
out.

[Jeff Strickland]

There are two ports, a High Side and a Low Side. The ports are different
sizes. You cannot connect to the wrong port.

Buy a can of R134a and follow the directions for NORMAL user service of the
system. For system repairs, this not gonna work, but to refresh the system,
it is fine.

"Michael" <mrda...@gmail.com> wrote in message

news:f95a3ab9-43a3-46ba...@nl1g2000pbc.googlegroups.com...

[NM5K]

On 5/25/2012 12:38 AM, Michael wrote:

>
> I suppose. I think they're also called Suicide Cans? =)
>
>
>> MAKE SURE YOU KNOW WHICH IS THE LOW SIDE BEFORE ATTACHNG THE CAN!!!!!!!!!!!!!!!!!!!!!!!!
>
>
> I am guessing... just a guess... but... I think I want to avoid the
> one that has a letter "H" on it.
>
> Besides, I hear the fittings won't fit on the HIGH side.
>
>
>> I have also wrecked a compressor with this stuff.
>
>
> Oh that reminds me. Should I get Toyota-branded R134A? Synthetic?
> Wal-Mart stuff? Car Quest?
>
> How did you wreck a compressor anyway?

They don't like liquid..
One can use no gauges if the vehicle has a sight glass, but it
may not.. My Corolla doesn't have one. :(
So you oughta buy the gauge..
One note, to get an accurate reading of the low side pressures,
and also to speed charging, you will need to get the engine off
idle.. About 1500 rpm or so should do it.. Just watch the pressure
dive when you give it the gas.. When it bottoms out, you have
enough rpms..
Also.. purge the lines before you charge.. IE: crack the
hose connections when connected to the system as to bleed out
the air that is on the hoses. Ditto for the charge hose from
the can. You don't want air getting into the system.
Air is a non condensable, and will cause excess high side
pressures.
If the low side line has a good sweat back, it's pretty close.
If freezing frost, or warm with no condensation, it's low.
The evaporator coil temp drops as you get low on refrigerant,
which causes moisture to freeze.
Also, when charging, turn all the inside blowers on full blast.
Front and back.
It doesn't matter what brand.. 134a is 134a..

[Jeff Strickland]

"Michael" <mrda...@gmail.com> wrote in message

news:07f22a29-fefb-4154...@t2g2000pbl.googlegroups.com...

On May 23, 11:05 pm, Michael <mrdarr...@gmail.com> wrote:
> I have the exact same problem as this guy, and I'm wondering if the
> solution is the same.
>
> http://www.toyotafans.net/2004-sienna-rear-ac-unit-not-cold-t4400.htm
>
> I've seen cans of R134a at the store, and I'm wondering how difficult
> this is to do. What are the specs on the minimum pressure at the low-
> side charging port? This doesn't seem to be specified in the Haynes
> manual I've got.
>
> I'm guessing I should get a can of R134a that has a pressure gauge, so
> I'll know how much refrigerant I need to add... if any.
>
> Also, where exactly is the low-side charging port? Again, the Haynes
> manual isn't very clear about *where* it is.
>
> Thanks,
>
> Michael


I went over to Wal-Mart, and I noticed the cans with a pressure gauge
have a nice table printed on the can as to what the pressure should
be, depending on the ambient temperature. I also noticed they sold
cans without a pressure gauge (which were half the price as the ones
with a gauge). How on earth would you know when to stop, without a
gauge?!

+++++++++++++++++++++++++++++++
You would not know unless you already owned a pressure gauge. Buy the can
with the gauge, then move the gauge to a new can next year. Honestly, you
should not need a new can every year, but the point is to save the gauge and
use it the next time you need another can.

[Jeff Strickland]

"Ralph Mowery" <rmower...@earthlink.net> wrote in message
news:w4ednSwXFe2kDCLS...@earthlink.com...

>
> "Michael" <mrda...@gmail.com> wrote in message
> news:1d956ab8-6bee-416a...@ra8g2000pbc.googlegroups.com...
>
>
>>How did you wreck a compressor anyway?
>
> The Low side is usually the larger pipe.
>

The Low Side is ALWAYS, not usually, the larger pipe. The Low Side and the
High Side are different sizes precisely to prevent connecting the gauge to
the wrong side.

[Ralph Mowery]

"Jeff Strickland" <crwl...@yahoo.com> wrote in message
news:jpobvb$9qd$1...@dont-email.me...

I have never seen one that wasn't. I just try to advoid some words such as
ALWAYS.

The valves are now differant sizes. Older cars used the same size valves
and the cans were blown up because of the higher pressure side that some
hooked to it. This is why the valves are differant, but not the pipes.

[Jeff Strickland]

"Ralph Mowery" <rmower...@earthlink.net> wrote in message

news:5M2dnXrVxfqgJiLS...@earthlink.com...

R134a ports have always been different sizes. Some R12 cars might have had
ports that could be confused, but I was not playing with R12 so I can't say.
But I've never seen a R134 system that was not both different from high to
low, but also different than R12 so there is no way to put R12 in without
working hard to do lots of things wrong.

[larrymo...@my-deja.com]

Haynes sucks. Chilton's sucks. AutoZone.com sucks but is free, so try them.
PDFtown.com has some Toyota factory manuals.

A website dedicated to car A/C: www.aircondition.com

Don't R-134A systems use different size fittings for the low and high sides, meaning you don't have to worry about this? But to confirm, run the engine at about 1500-2500 RPM with the A/C on high, and feel around the charging ports. The low-side port is cold, the high-side port is hot.

You really should get an R-134A guage set and a couple of A/C or food thermometers and charge when the outdoor temperature is around 70F - 80F. Some car A/C systems are really touchy about the right amount of refrigerant, so shops will often pump out all the old gas and weigh the amount of gas they put in.

DO NOT OVERCHARGE THE SYSTEM!

This is my half-arsed way of charging:

Check the accuracy of the 2 thermometers by putting them in a glass of well-stirred ice water while their tips touch, to verify that they read identically. Tape the tip of one thermometer to the inlet pipe going to the evaporator coil, the other to the outlet pipe. This should be near the firewall. Make sure the thermometer tips make good contact. Run the A/C on high and idle the engine at about 1500-2000 RPM, and the temperature readings should drop. The outlet temp will be higher than the inlet if the system is undercharged. Open the R-134A can's valve slightly to SLOWLY charge the system until the outlet temp is almost as cold as the inlet temp, or the pressure readings are right, whichever comes first. Try to charge while the outdoor temp. is around 70F - 80F because in hotter weather you need to undercharge the system to prevent excessive pressure. Before connecting the hose to the low-side charging port, open the R-134A can's valve slightly, to purge the air out of the system, and don't close the valve until hose fitting is attached.

[larrymo...@my-deja.com]

On Friday, May 25, 2012 9:26:21 AM UTC-7, Jeff Strickland wrote:
>
> I went over to Wal-Mart, and I noticed the cans with a pressure gauge
> have a nice table printed on the can as to what the pressure should
> be, depending on the ambient temperature. I also noticed they sold
> cans without a pressure gauge (which were half the price as the ones
> with a gauge). How on earth would you know when to stop, without a
> gauge?!

Temperature difference between evaporator inlet and outlet pipes, emphasis on DIFFERENCE. If you rely on pressure alone you stand a good chance of overcharging the system, especially in warm weather (not that going by evaporator inlet/outlet temperature difference alone will spare you from that), and apparently it takes only a few PSI of overcharge to hurt the cooling performance noticeably.

The directions probably mention always keeping the R-134A bottle upright so that only gas gets into the A/C, not liquid, and placing the bottom half of the bottle in a pot of warm water (about 90F - 110F) to keep the pressure up (bottle will otherwise get cold enough to form frost on the outside). Make sure you have room in the engine compartment to keep the water pot upright, even while the engine is running and shaking.

BTW buy plain R-134A, nothing containing leak detection dye or compressor oil.

[Michael]

On May 26, 5:02 pm, larrymoencu...@my-deja.com wrote:
...

> You really should get an R-134A guage set and a couple of A/C or food thermometers and charge when the outdoor temperature is around 70F - 80F.  Some car A/C systems are really touchy about the right amount of refrigerant, so shops will often pump out all the old gas and weigh the amount of gas they put in.
>
> DO NOT OVERCHARGE THE SYSTEM!
>
> This is my half-arsed way of charging:
>
> Check the accuracy of the 2 thermometers by putting them in a glass of well-stirred ice water while their tips touch, to verify that they read identically.  Tape the tip of one thermometer to the inlet pipe going to the evaporator coil, the other to the outlet pipe.  This should be near the firewall.  Make sure the thermometer tips make good contact.  Run the A/C on high and idle the engine at about 1500-2000 RPM, and the temperature readings should drop.  The outlet temp will be higher than the inlet if the system is undercharged.  Open the R-134A can's valve slightly to SLOWLY charge the system until the outlet temp is almost as cold as the inlet temp, or the pressure readings are right, whichever comes first.  Try to charge while the outdoor temp. is around 70F - 80F because in hotter weather you need to undercharge the system to prevent excessive pressure.  Before connecting the hose to the low-side charging port, open the R-134A can's valve slightly, to purge the air out of the system, and don't close the valve until hose fitting is attached.

.....

Thanks to everyone for the advice. This is embarrassing, but I think
the A/C is working properly. I didn't realize that for the REAR AC to
work, the FRONT AC button has to be on. I thought that if the rear
knob was pointing at the blue AC button, that should activate the rear
AC. But I didn't realize the rear AC shares refrigerant with the
front AC until I started researching the "problem".

When the front AC is on, the rear blows noticeably colder. I'll do a
temperature check with my thermocouple next time I get a chance, but,
yeah.

Thanks!

Michael

[Jeff Strickland]

"Michael" <mrda...@gmail.com> wrote in message

news:30363381-2102-418c...@ra8g2000pbc.googlegroups.com...

+++++++++++++++++++++++++++++
Yes, for the rear to work, the front has to be on.

[Daniel who wants to know]

"Michael" <mrda...@gmail.com> wrote in message

news:f95a3ab9-43a3-46ba...@nl1g2000pbc.googlegroups.com...

>I have the exact same problem as this guy, and I'm wondering if the
> solution is the same.
>
> http://www.toyotafans.net/2004-sienna-rear-ac-unit-not-cold-t4400.htm
>
> I've seen cans of R134a at the store, and I'm wondering how difficult
> this is to do. What are the specs on the minimum pressure at the low-
> side charging port? This doesn't seem to be specified in the Haynes
> manual I've got.

As mentioned, a refrigerant's temperature and pressure are directly related.
Pure propane (R-290) is always 0 PSIG at -44° F, R-134a is always 0 PSIG
at -15° F

R-134a is always 28 PSIG at 32° F, hence you want the low side pressure as
close to 28 PSI without going under.

> I'm guessing I should get a can of R134a that has a pressure gauge, so
> I'll know how much refrigerant I need to add... if any.

The cheap gauge that the cans have tell you nothing, cars are charged by
weight of refrigerant from a vacuum. Attempting to "top off" a partially
charged system is always a guessing game.

This is especially true on vehicles like mine which have a variable
displacement compressor, these regulate the low side pressure without
cycling so it will always be at the set point all the way from having less
than an ounce of liquid refrigerant up to being slightly overcharged, making
that gauge meaningless.

>
> Also, where exactly is the low-side charging port? Again, the Haynes
> manual isn't very clear about *where* it is.
>
> Thanks,
>
> Michael

Barring a weight/mass charge spec then a fixed orifice system is charged by
suction superheat, this is what "larrymoencurly" is measuring with the 2
thermometers, but it is more accurate to use the temp scale on a good
pressure gauge along with the thermometer on the evap outlet. IE if the
gauge says the refrigerant is boiling at 32° F in the evaporator and the
thermometer on the suction line reads 42° you have 10° of superheat. Some
positive superheat is required to know for sure that no liquid is making it
back to the compressor inlet, but too much superheat means that only part of
the evaporator is evaporating refrigerant, and you want as much of it in use
as possible for the coldest vent temperatures and best dehumidifying.
Suction accumulators help to keep liquid from getting to the compressor.

Expansion valve (TXV/TEV) systems are charged by liquid subcooling because
the valve controls the suction superheat automatically, this requires a high
side gauge with a temp scale and a thermometer on the liquid line. Once
again if the gauge says that the refrigerant is condensing at 100° but the
liquid line is only 80° you have 20° Positive subcooling is required
because vapor bubbles in the liquid to the expansion valve impair its
function, but once again too much subcooling means that the liquid is
backing up into the condenser and reducing its effective size. Liquid
receivers help to keep a solid column of liquid (no vapor) to the expansion
valves. This is also the reason for the sight glass, to let you know if
there are bubbles in the liquid.

Luckily with cars subcooling and superheat will be correct if you charge an
empty functioning stock system by weight to spec.

[uncle_vito]

"Daniel who wants to know" <m...@here.edu> wrote in message
news:jqgt3q$f6j$1...@dont-email.me...

I am impressed with your knowledge. Is variable displacement fairly common
in cars today. I own Toyotas. Is that what they use. I have noticed no
cycling. I have noticed also that A/C systems seem to last the life of the
cars. The old GM systems from the 70-80's used to crap out or burn up a
clutch seemingly all the time.

[Michael]

On May 27, 8:05 am, "Jeff Strickland" <crwlrj...@yahoo.com> wrote:

...

> Thanks to everyone for the advice.  This is embarrassing, but I think
> the A/C is working properly.  I didn't realize that for the REAR AC to
> work, the FRONT AC button has to be on.  I thought that if the rear
> knob was pointing at the blue AC button, that should activate the rear
> AC.  But I didn't realize the rear AC shares refrigerant with the
> front AC until I started researching the "problem".
>
> When the front AC is on, the rear blows noticeably colder.  I'll do a
> temperature check with my thermocouple next time I get a chance, but,
> yeah.
>
> Thanks!
>
> Michael
>
> +++++++++++++++++++++++++++++
> Yes, for the rear to work, the front has to be on.

And, yeah, I finally got my thermocouple out and the rear is working
quite well.

I measured bet. 80 and 85 degrees with just the blower on, then when
the AC started, it dropped to around 60 or so... then as we drove some
more, I gave the thermocouple to the kids, who said the lowest
temperature they got was 30 degrees (?!!) I still can't believe that,
but it sure feels cold so it's good enough for me.

Thanks everyone!

Michael

[hls]

"Jeff Strickland" <crwl...@yahoo.com> wrote in message

news:jpogho$79h$1...@dont-email.me...

>
> R134a ports have always been different sizes. Some R12 cars might have had
> ports that could be confused, but I was not playing with R12 so I can't
> say. But I've never seen a R134 system that was not both different from
> high to low, but also different than R12 so there is no way to put R12 in
> without working hard to do lots of things wrong.
>

When you convert from R12 to R134a, you use adaptors to change the ports.
At least, you should do it. I can imagine that jakeleg mechanics do some
other
monkey business.

Put your finger on the tubes with the unit running. The inlet should be
substantially
cooler than the high pressure side.

Use a damned R134a can with a gauge attached, at the very least. The
instructions
are clear on the kit, even for the least of these my brethren.

I have seen (and done) input of liquid coolant on the compressor by trained
mechanics.
It is a little faster, but it absolutely can be dangerous to the compressor
and associated
parts. If you are a beginner, dont even think about it. Input only vapor
phase
coolant.

Take your time.
Take your time!!

There is no rocket science to AC systems. But you had better know the
basic
fundamentals.

[hls]

"uncle_vito" <uncle_v...@yahoo.com> wrote in message
news:4fcc2cad$0$2989>>

>
> I am impressed with your knowledge. Is variable displacement fairly
> common in cars today. I own Toyotas. Is that what they use. I have
> noticed no cycling. I have noticed also that A/C systems seem to last the
> life of the cars. The old GM systems from the 70-80's used to crap out or
> burn up a clutch seemingly all the time.

Some of the GM compressors had well known shaft seal problems. They
started leaking early in life. There were, I believe, aftermarket or
redesigned,
seals that would stop this problem.

I never had any problems with clutches. Compressors beat them to the punch.