1998 Buick Regal ac pressures are weird

1998 Buick Regal has strange readings on the gauges. 80-85 degree ambient air temp, low pressure is 60, high is 125. I have 100 lbs of static pressure in the system with the engine off. I am getting some cool air, but I would expect that the high side pressure is not high enough to cool well. Do I have a plugged orifice tube? Is my compressor not compressing enough? Or is my refrigerant low and causing the problems somehow?

Your high sounds low and your low sounds high. Static pressure sounds okay, maybe a little high, but you can’t really tell that much from it. It could be contaminated refrigerant, a bad compressor, or ?? When was the last time it worked normally?

It worked ok last summer. It would function properly, but it had a leak. I charged it, adding dye, to try to locate the leak, but now it is doing weird things with the pressures. If I locate where it is leaking, I will fix leak, flush what I can, start fresh with oil, and recharge. I just can’t figure out what it going on with my compressor.

I thought perhaps a plugged orifice tube would cause the compressor to look like it is not working enough…

It sounds like a failing compressor.

I agree. Bad compressor. A plugged orifice tube would cause the high side to be way high and the low side to be near normal.

It’s the compressor.


Static pressure about 100 psi with ambient temp 85* sounds like a full charge. High side only climbing to 125 means the gas is not getting compressed.

You have all the symptoms of a failing compressor. If the orifice were plugged, you would see lower low side pressures, but then the question would be what is plugging the orifice?

After you replace the compressor verify the cooling fans are working properly. Excessive pressure caused by poor heat exchange at the condenser will kill a compressor pretty quickly.

If your compressor failed, it’s also likely your system is full of fragments and other crap that will be difficult to remove. If you want to restore the system to normal operation, you’re going to need the system flushed, a new dryer, and possibly a new condenser, at least if you want the new compressor to last. It may be a condition of the warranty if you buy a new or reman unit.

The cooling fans are working, but the compressor could be failing due to ripe old age. The car has about 205000 miles on it.

Used compressor. $50

Why buy a used compressor? He already has one. It’s currently installed on the car and not working.

@Cavell how would you know the used compressor wasn’t the original part from a 300K car?

Every part a salvage yard sells is “guaranteed to be good”, or so they say… :wink: