The radiator [1986 IROC-Z: single] fan doesn't want to go on sometimes and I've been told the sensor is crapping out, but with a small tap on it, it goes back to work. Sometimes I just start the car, drive a little, and the temp gauge shoots up to 220 and then the AC compressor starts turning on/shutting off b/c it's too hot. I installed an auxilary for the front of the radiator which will help only if the main one is on.

What can I do to fix this problem? I've already spent major bucks on putting in a new condenser and it's going to be hot in Houston, TX soon...

 

When you say with a small tap on it, it goes back to work. Are you referring to the sensor or the fan? If you are talking about the sensor, that should be a good indication that something isn't right with it. If you are talking about the fan, same thing applies.