My A/C compressor will not come on. I can jump the relay and get the clutch to kick on. The PCM is seeing the request from the A/C switch in the dash, but the PCM is not sending the request to the A/C relay. I traced the DRK GRN/WHT wire from the dash to the PCM, and then from the PCM to the relay. 12 volts into the computer, nothing out of the computer. I tried to bypass the LP switch by jumping the RED/BLK wire to the GRAY wire(5 volt ref) but A/C relay wil not kick on to engage the clutch. How many volts is the RED/BLK wire on the LP switch supposed to have when the LP switch is working properly, I assume 5 volts. If anyone can assist me in troubleshooting this circuit I would greatly appreciate it. TIA Rob.

 

The voltage on the red/blk wire varies, but it won't be more than 5 volts, since that is the reference voltage from the pcm on the gry wire.

I have heard of people having to reset the pcm after adding refrigerant, so you might even try that.

 

Thanks Shoebox, I knew you would chime in with some advice, I'll try that. I was also thinking that the PCM might have the A/C off or something. I just did a cam and stuff and the computer is from Brian at PCM for Less. I sent him mine back as the core. I'll go and try to reset the PCM. Thanks, Rob.

 

Reset the PCM, no luck. Any body else got any ideas, Shoebox anything else to try? Thanks, Rob.