aa7kn

Well sorry to beat a dead horse but I just can't find an answer to my problem. I have a 1991 XJ 4.0 5 speed. the A/C all works great and the Aux fan actually does work when I turn on the A/C. The problem I am having is that the Aux fan does NOT turn off when I turn off the A/C. It used to, but now it doesn't. I have checked and replaced the A/C and Aux fan relays. the only way I can turn off the fan after I switch off the A/C is to turn off the engine. when I turn the engine back on the fan stays off. only won't shut off after turning off the A/C. Most Aux fan problems are that it won't come on, mine is that it won't shut off when the A/C is turned off....any ideas ? thanks in advance.

aa7kn

maybe I found the problem. I noticed that before it warms up, the fan works correctly and I turn on and off the A/C. but after it gets to operating temperature it will not shut off when the A/C is switched off. I think the Thero switch in the thermostat housing might be malfunctioning, it might be closing way to early causing the fan to run. I will check the switch with a multimeter next time we drive and it is warmed up. it never gets over the mid way scale reading so the switch should be open all the time. any thoughts ?

BlueRidgeMark

IIRC, the fan sensor switch and the gauge sensor are two different beasties. If that's correct, then you can have a normal gauge reading and a whacko fan behavior.

aa7kn

yes I agree, and I did change the switch on the thermostat housing which is the one for the aux fan and it still won't shut off when I turn off the A/C and the gauge at the normal reading. maybe the Low pressure switch for the A/C is sticking, but I am not sure where it is. can some one please tell me where the Low Pressure A/C switch it located on a 1991 4.0 ?