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A/C Accum. Warm ?

kourso on Sat July 12, 2008 6:20 AM User is offline

Year: 1994
Make: Chevrolet
Model: Silverado
Engine Size: 350
Refrigerant Type: 134a
Ambient Temp: 86
Pressure Low: N/A
Pressure High: N/A
Country of Origin: United States

My pickup air conditioner accum. is now running warm or barely cool, if any coolness. Where previously it was real cold, sweating profusely. What could be the cause of this sudden change. The a/c vent temp. is fairly cool but not as cold as it once was. I had to replace the accum. cycling switch because the compressor wasn't cycling properly or at all with a normal freon charge on the system.
My mother in law's Lincoln Towncar had a/c work done on it recently and the accum. is also running warm as well. The mechanic told me that he doesn't go by a cool/cold accum. when doing a/c work.
I can tell the a/c doesn't work well on hot days but is much better at night when it is much cooler.
So both of these vehicles had cold accum. previously and now they are not, plus the a/c's are not nearly as efficient as they were. What needs to be done to correct this problem and what is the cause ?
I live in South Louisiana, plenty of heat and humidity.
Thanks,
Kenny

Chick on Sat July 12, 2008 6:26 AM User is offlineView users profile

You need to find and fix the leaks..Refrigerant isn't consumed like gasoline, so it's going somewhere..This is however an educated guess, since you don't list pressures.. You should also shop around for another mechanic... Hope this helps...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

raylo on Sat July 12, 2008 7:21 AM User is offline

Another thing to check is the actual pressure that your systems cycles at. If your new cycling pressure switch cycles the compressor off at a higher psi the temps will be warmer. I am battling this issue now myself. My old switch cycled at 20 psi and the system was freezing up after I installed a reman comp. I got an aftermarket switch from AA and it is cycling off at about 24 psi. Even though it is labeled as an R-134a part that seems more like R12 pressures and duct temps won't go below 47 deg F when before they were near 40.

I am not sure what to think of my situation yet. I still think it is a lame compressor that can't pull down through the setpoint of my OEM cycling swicth setpoint quick enough to keep the system de-iced. Rather it lingers in the 22 psi range which causes freezing. Then with the higher psi aftermarket swich no freezing, but a/c isn't as cold as it should be.

Here is a reference I found as to the proper cycling switch setpoints. The lower numbers are the "off" cycle and the higher when it should kick back on. Wouldn't hurt for you to hook up some gages and operate the a/c on a low load (max a/c, low fan) to most quickly observe the cycling pressures. In my case the OEM swicth is a lot closer to the 21 spec than the aftermarket piece. You might have a similar issue.


http://autoacrepairs.com/cycleswitchinfo.htm

GM Tech on Sat July 12, 2008 10:38 AM User is offline

A warm accumulator is a sure sign of low charge--or a bum pump- certainly os not performing as designed- your mechanic is making excuses for his inexperience or his not wanting to make it right for you. Pressure would be helpful to determine which one-- From here, I would say you have a leaky system- that needs to be found and fixed and recharged to spec....

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

GM Tech on Sat July 12, 2008 10:38 AM User is offline

A warm accumulator is a sure sign of low charge--or a bum pump- certainly os not performing as designed- your mechanic is making excuses for his inexperience or his not wanting to make it right for you. Pressures would be helpful to determine which one-- From here, I would say you have a leaky system- that needs to be found and fixed and recharged to spec....

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

mascas on Sat July 12, 2008 4:10 PM User is offline

Sounds like a low charge to me. I don't understand what your mechanic is saying, or why he just wouldnt DIAGNOSE the problem.

kourso on Sun July 13, 2008 4:42 AM User is offline

Hey Thanks Guys for the quick replies,
Am I correct in thinking that the problems on the warm accumulators is probably a low charge condition on each?
I was also suspecting a possible blockage on the orfice tube and/or air in the system. I will hookup the gauges and see what suction pressure they have and let you know but it is strange for the accumulators to be so warm where before the a/c work it was real cold and sweating plenty. I do see the evap. cores on each vehicle is sweating pretty well in our S. LA humidity and leaving a good stream of drainage water even with the warm accum.
I know the vehicles compressors are staying with the clutch engaged 99% of the time without disengaging. I would think that the a/c system suction pressure must be sufficient for that to be the case.
But I rather see the accum. get pretty cool to cold, I always have thought of that as a good sign of a/c operation.
Do you want the comp. discharge pressure as well?
I really appreciate all of the great advice.
Kenny

kourso on Sun July 13, 2008 4:52 AM User is offline

Even when I have added freon to the system, the accum. does not get any cooler. I might possibly see a couple of degrees cooler but it is still at best room temp. The other day the accum. and suction line from it was like warm or a touch hot? The compressor was engaging on/off and I knew that the system press. had to be too low. How do I determine how much to add by suction press. using a gauge set? Should it be 25# or 30-35#. I do not know what should be the correct suction pressure. And I have no way to measure/weigh how much is in the system at any time or to pull out/recover the freon. I just add enough to get the compressor engaged fully and adjust with the a/c vent temp. to get a good air temp. I have checked the disc. press. to make sure it isn't too high.
I know I am wrong on doing it this way but what is a better way?
Thanks,
Kenny

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