Ok first off, it's an 03' Cavalier 2.2L SFI DOHC 4cyl.

The A/C wasn't working when I bought it, no biggie right? WRONG. I cannot figure this thing out.

Here's what I know so far:

The main problem is that the compressor clutch does not engage when I turn on the A/C. I know that the Clutch Relay is fed power by the ERLS fuse. This fuse is GOOD. The Relay is getting 12V at the designated two terminals. I also know that the Relay is good because I swapped it with the Fuel Pump Relay. Both work.

The problem here is that the PCM is not sending a ground to the Relay. When I ground the terminal that's supposed to be grounded, the Compressor kicks on and pumps out cold air!

So I thought maybe I'm low on Refrigerant. I hooked up the high and low side and jumped the relay to engage the compressor. I verified that the cooling fan is on and checked the pressure in the A/C system. I found that I am NOT low on Refrigerant.

Next, I checked to ensure the Pressure Transducer is getting 5V which it IS, and I then verified that it is sending voltage to the PCM, which it IS.
The PCM receives 0.7 volts when the compressor is NOT running, and 1.4 Volts when the compressor IS running. To be safe I went ahead and swapped out the Pressure Transducer and it does the same thing.

While I was at it, I swapped out the Orifice Tube and the Accumulator. I drained the system, vacuum pumped it for 1 hour, recharged it and STILL NO CHANGE.

I am about ready to lose my mind. Any suggestions???

 

Does the little green light come on when you push the A/C button?

 

I suppose you could always ground it manually with a switch added to the dashboard, run from A/C compressor plug to ground.