Rip It

My car is in a shop having the ac fixed. Rebuilt compressor, new dryer,new expansion valve, and new belt installing R-134A. The problem is it cools at 2000rpm not at idle. Also at idle the low pressure side pressure goes way high (what ever that means). At 2000 rpm pressures are normal. The highly recommended mechanic thinks the compressor is the fault. He is also working the same issue on a carrera. Any ideas would be appreciated.

m73m95

I would also say the compressor.....but I am not the best person to answer this.

I'll bump you so someone more in the know will answer.

CurtP

Is the compressor cycling? What is the pressure on the low side with the compressor running? If it over-pressurizes, it will shut off the compressor and you'll get the compression cycling which will make the low side go down, spike, then down again.

You should be around 30-35psi on the low side with the compressor running. The usual range for R134a is 25-45psi, but 25 is too low and 45 is too high for these cars.

Rip It

I believe the mechanic said the low was 80 at idle, but not positive of that number. I am positive he said no cold air at idle and that the low side was too high. At 2000 rpm pressures were normal with cold air from vents, but not as cold as it should be but acceptable. The heat index this week has been in the 100's with lots of humidity. My ac had been degrading beginning this summer, not very cold vent air at a stop/idle, driving it worked great, and then the compressor froze up. With all that's been replaced, including a new condensor(Gibson...Gilbert Brand) with higher air flow 3 years ago. Could a compressor cause these symptoms. Anyway its a complex system with climate control and all the sensors etc.
Last I heard he has requested another compressor. I will pass on any info that might help fix my car. THX. PS the plastic clip is intact, heater valve has vaccuum and holds it. Low side is wacked.

CurtP

GOOD GOD MAN! 80 PSI with the compressor running? It's WAY overfilled. Have your mechanic evacuate until you are at 35psi on the low side with the compressor running. I bet there's nothing wrong with your compressor, unless your mechanic fk'd it up by overfilling. I overfilled too (although not quite as high as you) and got very little cooling.

If your mechanic can't figure it out, send me a PM - I'll give you a hand getting the charge right. I'm over in VA Bch, off of Kempsville.

CurtP

Forgot to ask - are you coming out to the autocross event this Sunday in Pungo?

lee101315

How do you know its overfilled? If the compressor is shot, the low side pressure will be higher than normal, even if its filled to the proper amount.

It sounds like the compressor to me, considering everything normalizes around 2000rpm.

CurtP

If the compressor is running (and cycling) and there's 80psi on the LPS, then it's overfilled. If he's seeing 80psi, but the compressor isn't running, then the compressor is shot.

xsboost90

yeah did he put more than two lbs refrigerant in there? sounds overfilled to me. The compressor isnt able to pump that pressure until you up the revs...

lee101315

When an A/C Compressor is completely dead, in an extreme case, the low and high side will have equal pressure (like 60, for example).

What is the high side pressure? It shouldnt be more than 200ish with the condensor at 105 deg.

Rip It

I just spoke to the shop owner, new compressor on the way. Will post results when I hear something. Thanks to everyone for the help.

Rip It

I got my car back last Monday with another rebuilt compressor and it works as it should. Little Creek Service Center on Diamond Springs Road in Va. Beach did a great job! Very impressed by the fact they would not let me have it back until it was right. Charged me half of what they could have and half what I figured I would owe.