2001 Chevy Cavalier

[cap2620]

Hello all,
I have a 2001Chevy Cavalier with inoperative AC. Connected a gauge set, static pressure around 70 PSI both sides, operating pressure on the low side was around 25-27 PSI, high side 180. Ambient temperature was 80F.
From reading here it doesn't seem the pressure is abnormal, but yet there is absolutely no cooling. Since this is a used car, had it for about 2 years, I don't know the history of the AC but it did work when we first got it.
Thought maybe an evac and recharge might work, but it didn't. While charging the low side hovered around 25 PSI, high side was hovering around 100 PSI until I got near the required 1.5 lbs then it shot up to over 300 PSI !! Is that abnormal ? Ambient temperature was around 80F, car was running for quite a while during charging, electric radiator fan was operating normally. I read here about high side pressure could be affected by air flow across the condenser, I didn't try to mist it while charging to see if the high side pressure would go down.
Seems like the flow within the system is being restricted somewhere, crud build up somewhere? Compressor becoming toast? During evac oil didn't look like it was dirty, actually was bright green, looked like a UV or fluorescent dye (?).
Does this car have an expansion valve, fixed orifice or something else because looking at all the lines I can't see anything that would look like an expansion valve unless it's inside near the evap coil. Only thing I see under the hood is (what I believe) a high pressure cutoff switch near the condenser.

Thank you for your help.

[Nacho]

Cavaliers develop leaks on the compressor's shaft seal and body seals. Other than that, the system is pretty reliable and performs quite well. Are you absolutely positively sure you didn't add more than 1.5 lbs? Maybe you want to do it all over with real gauges and, if possible, a scaled charge. Compressors on these cars don't clog the system. I'd say it's overcharged.

[GM Tech]

It has an orifice tube at condenser outlet-- you have an air flow problem-- if anything is clogged- it is the air path through the condenser...

or too much refrigerant like Nacho said.....

[cap2620]

Thank you Nacho and GMTech for the information. I purchased a set of decent gauges (didn't pay $200 for them though) and charged using the little 12 oz cans. I'll give it another look in a few days when my daughter is actually home for more than an hour

[cap2620]

Got a chance to look at this again. Evacuated, pulled a vacuum for an hour and recharged with 1.5 lbs of R134a. I got a scale and weighed so I was sure I charged with the correct amount. I also made sure I purged the yellow gauge line so air didn't in.
Results: low side pressure oscillated between 25 to 28 PSI, high side oscillated between 135 to 150 at around 750 RPM. The pressure oscillated at a rate of about every 2 seconds and the high and low sides changed in sync. Ambient temperature was 80F, duct output temperature 90F so .........................???
Static pressure equalized after 15 minutes or so to 100 PSI, both sides. The large line out of the evaporator coil into the dryer/accumulator was warm and the small line into the condenser was just barely warm.
Is the pressure oscillation an indication of a problem? Seems like the high side pressure is a bit low according from what I am reading here.

Thank you

[Nacho]

No compressor noise, a high suction, and little or no discharge pressure indicates either a failed compressor, or more likely, a defective refrigerant control valve. The RCV is easy to replace in the Cavalier. There is an article that refers to this concern on the knowledge base. Click on the link on top of this page.

[cap2620]

Thank you Nacho, read the article about the RCV, clearly written. Speaking of compressor noise (I checked this out today) there is a very faint buzz I hear when the pressure is fluctuating down, nothing loud just slight a buzzing sound.