Automotive Air Conditioning Information Forum

Hi I have a 2008 saab 9-3 and the ac compressor just turns on and off every few seconds. and dosent cooling at all. The pressures show... low side 20psi. High side 250psi and the temp was in the 90s. I believe these were static pressures. The ac was working fine. I had a little r134a added and then shortly after the ac went out!

Those are not static pressures, which we do not use. Static pressure would be/should be equal both sides

Saab wrote: ↑Wed Jul 07, 2021 8:30 am Hi I have a 2008 saab 9-3 and the ac compressor just turns on and off every few seconds. and dosent cooling at all. The pressures show... low side 20psi. High side 250psi and the temp was in the 90s. I believe these were static pressures. The ac was working fine. I had a little r134a added and then shortly after the ac went out!

I think the best way to approach this is to begin with the correct charge, which is 24 ounces of R-134a. Only then will the pressures mean anything. A professional shop can handle recovering the existing charge and recharging the system precisely to spec.

The pressures that you provided don't look like static pressures. I would expect both the high side and low side to be around 90 PSI at that ambient temperature range with a full refrigerant charge.

If A/C was working fine, why was refrigerant added?

The ac was blowing a little warm. So when I took it to the shop and had it looked at they said it was a little low. So some refrigerant was added. Then a few days later I was told my compressor was shot and I needed 1500 dollars worth of work. So currently the system has been evacuated of all refrigerant! If I was to recharge the system myself do I have to add more oil into the system? Thanks!

The answer to you question about adding oil is 'maybe.' It depends on whether any oil was recovered when the shop reclaimed the refrigerant. Usually, some oil comes out and collects in a graduated container attached to the shop's Recovery Recycle Recharge (RRR) machine, and an equal amount is put back in when the machine recharges the system. Unless you know how much oil came out at that time, it's guesswork about how much, if any, to put in.

These posts concern me more and more.

In general, shops adds refrigerant. Then the system has issues and it's a $1500 fix. Honesty, 95% of the time I could tell when charging if the system was that bad. Can see why so many tend to think a/c repair is as bad as used car salespeople. Not to say I have not seen a system fail shorty after like a hose repair.

I'm taking the car in for a second opinion on Friday. This mechanic thinks that there could be a blockage somewhere as if the first shop may have put a stop leak or something in the system. I currently have a new compressor, condenser, dryer, and expansion valve. Hopefully it turns out to just be maybe a clogged expansion valve!

If someone added stop leak then your troubles are just beginning.....