OK, I bought this truck with the Air Conditioner not working. The Freon is good according to guages. However the compressor will not kick on, or cycle. I took a power probe and made the clutch to check the 134a and the system works good, Ove traced it eown to the ground side of the Clutch Soliniod. Ive checked out or replaces the cycle, low and high pressure switches, and even Replaced the HVAC controls. And help or suggestions is appreciated,, This one has got me.
Thanks

 

dont know if this helps, but the pcm grounds the hvac relay.

 

Yeah Ive got a Print from GM, However is doesnt match perfect beings how they go back to only 98. If I had the PCM routing it would help a lot. Thanks though
That is where my print stops

 

This is for a 1996 C10.

PM me if you have any questions, or need a diff. diagram.

 

Thanks man, Well agter about another 3 hours of troubleshooting Thursday I found a shorte4d wire going from the high pressure switch to the PCM for the AC requested signal. It was a deal ground and as soon as you pluged the Heater control up it would fry it as well. Ive got it working now with a jumpewr and my new head should be in tomorow. Thanks for all the help. BTw it was shorted on the metal hanger that is mounted below thebrake booster for that large part of the harness that goes to the PCM. Thanks again fellas