AC abruptly quit
 

Driving around today the air conditioning was working fine. All of a sudden it just started blowing hot air. I went home and checked the system pressure. The pressure was 75 PSI, in the warning zone on the gauge. Now when I select an AC mode the whole car shakes.

My guess is a blockage in the line somewhere. Also sounds like a problem I will have to take it in for, considering the freon.

Anyone had this problem before?

Re: AC abruptly quit
 

If the refrigerant gets low enough the PCM will cut off the compressor. How did you check the pressure. It has to be checked with the compressor running. If the PCM cuts off the compressor it has to be reset before it will work again. Either pull the PCM fuse for a few seconds or unhook a battery cable. 75 PSI sounds like it was checked with the compressor off. 75 PSI is too high for a low side pressure and too low for a high side pressure.

Turn on the a/c while looking at the compressor clutch and you can see if the compressor starts. You should be able to see if it is making noise or vibrating. If it is I wouldn't run it any more until you get it checked. If your refrigerant has been leaking, oil leaks out with it. Over time, if you keep refilling without adding oil, the compressor can lock up due to lack of oil. If it seems to be working ok, you could add some refrigerant and see if it starts cooling normally.

Re: AC abruptly quit
 

I checked it with the compressor on. I was about to pump in a little more R134 if it needed it. I have added refrigerant twice in 10 years so it is possible some oil has escaped as well. I am out of town, so further diagnosis on the clutch will have to wait until next week. At this point I suspect the clutch was engaging and there is a problem with the compressor that is causing the car to shake when it is on.
Thanks for the input.

Re: AC abruptly quit
 

Just wanted to follow up on this thread with the fix for this problem.(In case someone else has it) It was the compressor clutch. It went bad and was no longer engaging or disengaging properly. The vibration was caused by the compressor clutch spinning off center as it was driven by the belt.
Just this week got it in to get fixed. Glad to have it back in normal driving condition after all this time.

Re: AC abruptly quit
 

Thanks for the update, I have a compressor clutch that I suspect is going and it's good to have the additional info you've provided here.