Hey I have a 1995 pontiac sunfire se 2.2l with 120000 and my car is overheating. Basicly when idrive my car it is perfectly ok but when i hit stop and go trafficsometimes my ac compressor disengages on its own and kicks back in and disengages again. but sometimes it will disengage for a few minutes and then the car will start to heat up. Now the radiator cooling fan works when the ac works but when the ac is not working the fandoes not turn on. i tested the fan about a week ago with the ac offand it turns on at about 224 degrees f which looks about 3/4 of the way hot on the gage (which i thought looked strange to begin with)but the other day it got up to around245 degrees with the ac off and the fan would not engage. I do believe that my compressor is leaking but when the ac is not on the fan should still turn on before it hits the danger zone. The only thing i can think of is the coolant temp sensor is bad which im going to replace. i checked the thermostat and it works because the upper radiator hose is hot telling me that its opening. Im wondering why my car overheats when the ac doesnt work. Will replacing my ac compressor stop my car from overheating or is there something else. Please help thanks in advance

 

I had exact same problem and was given a $800 quote for fixing it. But then at one note somewhere on the internet, I found that the computer in these cars sometimes starts acting crazy. Your sensor can't be bad because its the same signal going to computerand is feeding the gauge on the dash. So, if you can see the gauge going UP 3/4 means that your sensor is reading the (over)heating.
The solution for my car was FREE. Just disconnect the battery cable for more then 8 hrs OR try reseting it with code scanner.
Gud luck!