AC compressor won’t engage

Hi All,

First time poster… Got an oldie with 185k miles on it and the AC compressor will not engage. Swapped relays, checked fuses, put some refrigerant in the line so as to have some head pressure on it. The AC light in the switch comes on, wiring looks to be in tact, but no clutch. I would try jumping things and wringing out the wiring if I had a diagram. Recommendation’s for wiring diagrams without having to purchase a library?

Thanks!

 

So the A/C light comes on and does not start flashing correct?

 

Thanks Dm!!!

 

If the compressor won't engage but the light is on and not flashing if there's sufficent pressure (> 40 psi) in the system you either have a problem with the pressure switch/circuit or the evaporator thermistor/circuit.

The pressure switch is on the liquid line near the right side radiator support, note the system must be empty to change the switch if it is bad.

You can jump accross the switch terminals (careful not to spread the pins) and see if the clutch engages.


The connector for the evaporator thermistor is behind the glovebox just to the left of the cabin air filter opening.
Resistance chart for it is attached.