I've been having a few issues with 1 or multiple coolant sensors. By searching on AutoZone's website for parts, it seems there are 3 separate coolant sensors..

1. Duralast/Temperature Switch (TU174) | 1988 Chevrolet Celebrity 4 Cylinders R 2.5L TBI OHV | AutoZone.com

2. Duralast/Coolant Temperature Sensor (SU109) | 1988 Chevrolet Celebrity 4 Cylinders R 2.5L TBI OHV | AutoZone.com

3. Cooling Fan Switch - Radiator | 1988 Chevrolet Celebrity 4 Cylinders R 2.5L TBI OHV | AutoZone.com

I have found the location of the first two (both are near the thermostat), but I cannot seem to find the 3rd one.

Now, my problems are..

1. Radiator fan will not turn on by itself so it seems to have a problem with getting a little hot during idle at a stoplight, etc.. (I can force the radiator fan to turn on by turning on the A/C, and the fan does indeed work)(I say "seems to have a problem getting a little hot during idle" because it could also be that the sensor that controls the temp gauge on the dash is bad..)

2. When I start a cold engine, the temp will continue rising as it warms up, like normal, but it continues rising all the way to about 220-230 degrees, then it quickly drops back down to 150 or so. it may go back up to 220 one more time, but it eventually seems to settle once the engine has ran for a while

a few additional notes; I had a leaking radiator fixed 2 weeks ago, and also put in a new thermostat. I also tried burping the cooling system but that didn't do anything

the sensors are cheap (~$15 each) so I may just replace all of them and be done with it. I'd like to know the location of the 3rd sensor (the cooling fan switch) and also what exactly the first 2 sensors control.

Thanks

 

did you locate it? im having same issue