Pontiac Repair: a/c, ducet, engine computer

Question
2002 sunfire. A/c clutch will not engage when a/c turned on. R134 is at pressure, relays and fuses are o.k and light on dash switch comes on when you turn it to a/c. Crossed over relay terminals and clutch will engage but cooling fan not kicking in. Am i missing something obvious to look at.

Answer
Hi Tom:

That car has a pressure trans ducet in the hi side pressure line. If the system is full and it will not turn on that is the first thing I would look at. That sensor tells the engine computer the amount of pressure in the system. If it's not reading correctly it will not allow the compressor to turn on and also not allow the cooling fan to come on. When the pressure gets high enough it the engine computer then turns the relay on for the fan. If you had a scan tool you could look at that pressure reading and see what's going on. I have seen the wires to that sensor break off also the harness is a bit short and the rocking back and forth of the engine breaks the wires off. Good luck :)