got a 04 f150 lariat with eatc head unit. compressor dont kick on. checked fuses relay, ect.. i can ground the wire that goes to the relay and make the compressor kick on. it has a full charge. here is a list of what ive done so far. i have 12v from the control unit to the ip cluster via the vt wire. the can bus wires coming out of the ip cluster has 2.75v each. one of which is the a/c signal to the pcm. i have a otc genesis scanner, and it only tells me so much. most of which dont help. im stuck on weather its the pcm or ip cluster or control unit. i ruled out the control head after finding 12v coming from it to the ip cluster. i was almost sure it was the pcm, until i found the -can and +can wires only having 2.7v going to the pcm from the ip cluster. and i cant find anything giving me the voltages. i thought most signals voltages and ref voltages were 5v. but im a gm tech, so im not sure on fords. any one have a clue on how to test the pcm and ip cluster? one other thing i found odd is the temp gauge reads normal when you first turn on the ignition for 10-15 secs, then drops below cold. seems like it could be either the pcm or ip cluster. alldata is not that great for diag. and the otc genisis dont give alot of test or data for the hvac. so at this point im stopping due to the cost of parts. its a sheriffs truck, and they dont have alot of money to spend on repairs at this time, or i would send it to the ford dealer.

 

i really need some help with this. if anyone has any advise it would be great.