Clint's 944

OK, so I have been going back and forth on this a/c issue.....

To give a little background, I had a leak and I eventually found it. It was the expansion valve so I replaced it as well as the receiver dryer, vacuumed and charged. By the pressures, all was perfect but I still did not have cold air. After a couple weeks, I gave up and took it to a shop. They had the car for two days and they could not figure out was was wrong.

Here is where it gets interesting. They flushed the condenser thinking it had an obstruction. According to them, after they flushed it, the high side was now a little low and they thought the issue would be the compressor. After quite a few days of searching and checking, I realized the heater valve was open. I replaced that and fixed the mixer valve that was not moving.

Here is where I'm at...
My static pressures are perfect PSI to Air temp.
My running pressures are low on both sides. 10 psi on low/ 110 on the high.
If I charge the system, the low side will go up to 35 psi but the high side will float up and down around 175-200psi. Even if I increase the charge the low side to 40-45psi the high side stays the same.


So, should I replace the compressor now or could it be something else!!!
Any ideas?

Mike C.

You should get cold air with 35 low, 175 high. I'm not that familiar with climate control systems but it sounds like it could be an issue. Can you tell if the low pressure side hose is getting cold? If it is then I would suspect CC or a flapper door not moving when it should. How often does the compressor cycle?

75ohm

High side should get hot and the low side should get cold, much like Mike said... you're taking in a charge and the pressures are decent...

Clint's 944

the low side will get "cool" not cold, but it does sweat alot of condensation.
The flappers/ fresh air vents all work. I even sprayed water on the condenser and still no cold air...

Clint's 944

OH, one other thing that might help...

I noticed the compressor does not "cycle". I hit the switch and the pressure goes down and stays there......

944Ross

It takes a while for the compressor to cycle, at least on mine, in hot weather. What are your fans doing? Do they kick up to high?

Has the car been converted to R-134a? I can't tell from your pressures.

Bri Bro

Measure the temp directly at the evaporator and the condenser to see what type of heat transfer the system is giving you. Also measure the outside air temp and the inside vent temp and post the results along with low and high pressure reading. That should be enough info to narrow down the problem.