Hello,

OK, so I thought my AC compressor clutch was gone because it would not engage when I jumped it directly to the battery. Turns out the positive battery terminal's bolt was so corroded that it would not conduct electricity!
So the AC clutch is good, and the AC cools if I jump the compressor directly to the battery. The AC compressor or fan will not turn on when the AC button is pressed inside the car. The HVAC fuse is good.
I noticed there is an AC compressor relay. How do I test it? Does anyone know which terminals do I jumper to get the compressor to come on?
Thanks,

Csaba

Test the pressostat switch, on the low pressure line just before the firewall. Turn on the engine and jumper the wire, the clutch should engage regardless of the pressure - if so, add R134a. If the pressure of the gas is already good, a new pressostat sw might be the cure.

Klaus
--
Always willing to listen, just not able to take direction.

The pressure is good, I just charged the system. I tested the pressure switch, and it works. I tried to jump the pigtail connector too, just for kicks, but no joy, the compressor still does not come on.
Is there anything other than the relay that's left?
What is the 3 prong electrical switch close to the low-side pressure port?
Thanks,

Csaba

This is a common problem when the refrigerant pressure is low. There is a low pressure safety switch the turn off the AC clutch in the refrigerant pressure is low. It might still blow cool air if you jumper the clutch if it low not out. Try adding freon first. There is also a relay but they are pretty reliable not to say that they don't fail.
When you add the freon, run the AC, don't worry about the clutch at first. When you add the freon the pressure from the can will usually boost the pressure enough to automatically start the clutch. Once it starts the pressure may drop back and the clutch will start cycling on and off. Keep adding freon it will still be low. Some freon cans have cheap gages on them that will show you the approximate freon level. That's the cheap way.
Good Luck
Frunk