Thread: How to test an Air conditioning system

IIRC the pump has to be electric to draw the system down to 30Hg. Once there see if it holds that for 1 hour. If it does, then recharge and call it done. It's what I've always done and no issues so far.

If you have a leaking seal you will know it since the system will not hold vacuum. New seals should come with a new compressor. You could dye test the system to see if there are any leaks prior to changing the compressor again.

It is 65 degrees out and I just checked the pressure or charge level, and it reads at 35psi on a recharge bottle gauge, but the compressor does not engage. I do not know how accurate those gauges are and I am going to go buy a vacuum pump and gauge set. what is the proper psi for proper charge? Is there a way to test the compressor itself?

ok sorry but I let the car get to operating temp and the compressor is kicking on. I checked the pressure and it was fluctuating between 28- 32 or so. Does the car have to be running and the ac on, to properly check the charge level? I am just trying to verify that the compressor is definitely bad before I spend the money for a new one. I blows air, just not cold. The compressor does not make any abnormal noises.