Automotive Air Conditioning Information Forum

My son said the A/C quit. Sure enough, no cold air. The system has/holds pressure based on the strong PSST from the hi side valve. I wish i had found my duffer type pressure gauge before i started the car and checked to see if the compressor was running- it was, and when i turned off the A/C it stopped and when i turned it on it started again. It wasnt cycling on and off. It has dual climate zones but i had them synced and in auto mode. I turned the temp all the way up to hi and then all the way back to lo. The car cycled the airflow from dash to feet and back to dash as i did this. I took a pressure reading at the low side valve and it was about 90, (in the redzone )while the ambient air was 80. I did not feel any of the lines getting cold or hot.
I believe i have a working clutch and compressor based on this mornings observation (adding to what i observed last night). So, updating what i know: Static pressure in system after sitting overnight and at 70 degrees ambient is 65. When car was on and running(last night), the AC set to on the clutch would engage and pressure was 90 at 80 degrees ambient. The AC lines were both the same temp. I am assuming based on all info at hand now that the clutch and compressor are working. What is the most likely culprit, how difficult a job?

I'd get a REAL AC shop to pull out the R134a and WEIGH it, it's likely low. Then the shop will add UV dye and correct weight of refrigerant, and look for leaks, and then fix such leaks.

Do NOT blindly add refrigerant or especially any sealer or refrigerant containing sealer/"stop leak" !

Are those pressures low as i described? I was thinking they were about right? What should they be if working correctly?

callwill wrote: Sun Aug 10, 2025 9:20 am Are those pressures low as i described? I was thinking they were about right? What should they be if working correctly?

Disclaimer: I'm not an AC professional.

Static pressures (compressor not engaged) don't tell a whole lot, except a certain pressure must exist for the pressure safety switch to "close".

Both low pressure and high pressure values at about 2000 rpm can provide some information. "Typical" pressures at 2000 rpm after a couple of minutes at maybe 95F would be about 35 psi and 250 psi

Nothing changes when the AC is turned on. I can see the clutch spin up, but the pressure on the low side does not change. The only thing that happens is the static pressure goes up as the temperature rises. So im thinking the clutch and or the compressor are not doing their job.
A compressor solenoid control valve was mentioned in a search i did as being problematic. The valve is 45 bucks and it requires evacuation and refil to replace. An all new compressor with clutch and seals for the lines is 120(and it has a new controll valve in it). I think that is the route im going.