messing with my truck and noticed that the A/C clutch is not engaging at all. at first i figured that i had fried my HVAC controls when doing a LED retrofit. I just finished up installing e fans with a 3 relay setup as well. I am using a 2002 "156" OS and fans seem to work fine.

after messing with it a bit i found that i can engage the clutch (Fan comes on as well) with the scanner (HPtuners) when the truck is not running. as soon as i start the truck it no longer works. the HVAC control in the truck appears to be working fine, blower and blend doors all work and all lights come on (A/C, Recirc, Ect) . i have yet to start probing wires and checking voltage, just made me wonder where it will engage with the scanner as long as the truck is not running.

anyone run into this?

 

That can happen if your A/C charge is low.... If you jumper out your low pressure cutout, and it works, add a little refrigerant and get back on the road.