Hi guys, I'm new here. Nice site. I have a 2002 F250 7.3 Powerstroke with a newer compressor I put on 2 years ago. The ac was working fine. The truck got laid up for about 2 years because I went to prison - no bull. Anyway, when I got back home the ac won't come on. The fan comes on and if I short 12 volts to the compressor it works. My pressures are good. I have shorted the high and low pressure switches but that doesn't do it. Is there an ac relay in this truck?
Thanks for any info that you might have to offer.

 

Got this from another site - thanks to techomecho

The relay is under a black plastic cover on the driver's side behind the battery. There are a couple other relays under there.-------I would start by jumping the AC relay to see if the clutch will run, you do this by removing the relay and putting a jumper wire between 30 and 87 terminals, if the clutch runs then check to see if there is power on the 85 terminal at the relay and a ground at terminal 86 if all are good replace the relay. The terminal numbers are located on the bottom of the relay, be sure that terminal 30 has power if the clutch does not run.
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Faulty compressor clutch relay. Check to see if the relay is receiving voltage when the A/C is turned on. Also check the relay wiring and ground connections. If bypassing the relay with a jumper wire or routing battery voltage directly to the compressor clutch makes the A/C work, the relay is probably bad.

There are three relays in this area. I pulld all three, shorted each one on the terminals mentioned and the third one activated the clutch. Simply switched out for a felay from elsewhere and now the ac is working. So, there is a relay for the ac after all.