I think I know, but have no clue!

Okay, the car:

Chevy Corsica, 1994, 2.2 L engine, almost 200,000 miles

The Problem: The car overheats. The radiator fan doesn’t run when it should. The information about the temp makes it to the dash thermomoeter, so I don’t think it’s the sensor that’s bad. The fan blades freewheel (spin easily by hand), so I don’t think it is the fan motor. The only other option I can find in the Chilton’s is the fan relay. Great! That’s cheap and should be easy. However, there is no photo of where this relay is found. I know what it looks like because I can find the part in on-line parts stores, but where is it in the blasted car?!?

The temperature sensor that operates the fans may not be the same one that sends a signal to the temperature gauge.

The fan sensor is usually located in the radiator, while the gauge sensor in mounted to the engine. The output from the sensor can be tested.

You can test the fan motors by hooking them up directly to the battery with jumper wires.

The fan relay might be mounted in the fuse/relay box under the hood.

You have checked the fan fuse, right? And are you sure the thermostat is good?

I know the fan isn’t working because when I took it on the highway, the temp dropped quickly, but when going at in town speeds the temp goes up real fast, and I’ve let it idle and watched the temp rise and never saw the fan move. The plug into the fan also doesn’t show me where I could hook up the battery to test the fan motor. Where is the fan/relay box located under the hood? The only fuses I know are located in the cabin…

Your fan motor has been gone for some time. If $40 is too much to risk then I had better not tell you to get an entire car. At least get rid of the stupid Chilton manual and look in a Haynes.

OK, back up, major situation change. While I had it running and I was trying to follow spark (plus help someone else), the fan came on! However, the engine still was overheating. If this has been happening, it might be the Thermostat, but I’m still at a quandry for a fact that makes no sense to me: I can take this car on the interstate, driving up past 50 to 70 mpg, and the temp drops. I thought it was because more air is getting to the radiator, but if the fan is working (which it seems to be now), why does it overheat at the slow speeds only?