auxilary fan just staaays on

[bmwm42]

the ac should turn on regardless if the sensor is connected or not and regardless if you have a comp or not hooked up or not. i think your problem is solved

[Jaxx_]

thermo switches are just alternative switches for the relay to ground out and the power to turn on. I think you need to look at wiring schematics before you start touching more wires.

[ROLLingKING]

Maybe but not for this problem..ive never had a working aux fan so im also not exactly sure what to expect. The problem is the sensor! I tried one that i got from the junk yard and let my car sit till the gauge crept up to 3/4 and that sensor trigerred no fan.lol ill be ordering a sensor once i have a job again