So I've got a 99 3.9 and my compressor wont come on AT ALL, it was coming on fine and then all the sudden i went to recharge my air conditioner and it stopped coming on, even when you turn the AC on MAX. I checked the switch right on top of it, it is fine, idk where any other ones would be that i might need to check, maybe the pressure switch back by the firewall. Also i can turn it the clutch over by hand so i know its not locked up. any ideas?

 

sounds like you over charged it to me, and that is coming from a lisensed mobile a/c guy here. if you jumper the clutch, or jumper the preasure sensors what happens?

 

check your fuses and relays to.