Questions and Answers

Jeep Cherokee A/C Troubleshooting Q. I took your advice and tested the A/C on my 1990 Jeep Cherokee. It has 139,000 miles, 4.0 liter engine. On the low pressure switch I jumped the wires and the compressor clutch did not come on. I had power to the switch side of that plug. I unplugged the wire connector going to the compressor and hooked power to it and the clutch engaged and A/C blew cold air.

I hooked everything back like it was. From the low pressure switch going to the compressor is there anything in between that I need to check? Do you have something showing the complete A/C wiring diagram,where there might be a thermostat or something that is after the low pressure switch?

Any input would be very helpful. You have really helped me out on some other problems on this vehicle and it is greatly appreciated.

Thanks,
Rick

A. Okay, now we know the A/C low pressure switch is not the problem. So the next thing to check is the A/C Clutch Relay, mounted on the right shock tower. With the low pressure switch jumped, check for power at terminal 4, light green wire, and see if there is power there. if there is, the wire from the low pressure switch to the A/C clutch relay is good.

Now check for power at terminal 1, orange wire, and see if there is power. If not, the A/C clutch relay is bad. If there is, the wire from the A/C clutch relay is open.

Jumping terminal 2 to power and terminal 5 to ground (take the relay out to do this) should activate the relay.