Hi, I have a 1990 camaro RS and I'm having a problem with the radiator fan not kicking on when the car gets hot, thus causing it to overheat unless I turn the AC on. I've replaced the temperature switch that a lot of people suggested, and I replaced the oxygen sensor to fix another problem but could also have caused the overheating problem. Nothing worked. The car also had an idling problem which I fixed, but now when the car does get to the point where the fan SHOULD kick on, it doesn't and the car idles off again. I'm starting to think it might be an electrical problem and theres a wire shorting out somewhere causing it to not kick on and to make it idle rough. The car was a field find and I know that mice were in it at one point. Any suggestions on what it might be?

 

Find the relay that controls the fan, and bypass it with a test wire. If the fan turns on, your problem is the relay, or the signal to the relay. If the fan doesn't turn on, your (first) problem is between the fan motor and the relay.