Hello all. Longtime Saturn owner, first time poster. I've got a 95 SL 2 that I use to commute here in SoCal. (about 55 miles round trip each day on the freeway) 180 thousand + miles and it runs like a top. A couple of weeks ago it developed a whine in the A/C compressor. (sounded like an old GM power steering pump, just not so loud) I looked a a few on-line discussions and found it common. It was still cooling perfectly, so no real action required. Not so any more. Last couple of days I've noticed it's blowing air that's cool but not cold. Especially true in the afternoon when it's hot. Compressor clutch is engaging properly and staying engaged. Low side pressure is about 50 psi. (no guage to check high side) No obstructions or junk in condenser, and no overheating or other odd stuff in other systems. Key observation: The high pressure line does not get cold near the compressor. In fact, it's pretty hot to touch when the engine is running and A/C is on. Should I be looking for a new compressor?

 

OK -- we're missing the key reading of the high side pressure, but will try to cover your bases. The low side gauge reading should be closer to 35 than 50 ........

The high side line near the compressor will not get cold, because you are compressing the gas, causing heat. (higher than normal pressure on the low side of the pump will create more heat) The high pressure gas is cooled by passing it through the condensor assembly, turning it into high pressure liquid.

Standard causes such as you describe are one or more of the following -- restricted or blocked condensor fins -- refrigerant overcharge -- faulty condensor cooling fan -- engine overheating -- air in the system -- incorrect refrigerant.

You said the condensor was clean/clear, so that's out. You said the engine is running normally, so engine overheat is out. You said no odd stuff in other systems, so faulty condensor fan is out. You didn't mention recharging the system recently, so a refrigerant overcharge and wrong refrigerant is out.

Only things left are some type of restriction in the system, or air in the system, and with the compressor suddenly starting to make strange noises, either is possible .......

 

OK, thanks. Guess it's time for it to go to a pro for evaluation.

 

Yupper!

 

or buy a full set of gauges for a/c testing.

It's also possible that the schrader valve on the low side has developed a slow leak from pressure testing since these are designed to stay closed and sealed but after no use for 180K they can begin to not close properly.

Air in system = leak = air not as cold

 

If you have an Autozone nearby, get their rental gauges for about $100. When you return them, they'll refund 100% of your money.

 

Please keep us in the loop on your problem --

 

I have used successfully for a number of years now the R134 refill kit that includes the gauge and a can of R134. It plugs into the low pressure side and is adequate to refill the system when it is low due to leakage. There is only so much diagnostics that can be done with it but it does indicate when the refilling is accomplished correctly and I have successfully used it to convert freon systems to R134 usage.
For anything further than that you need more of a diagnostic tool.
Leakes and Shrader valves are big on going problems.