Why does the cooling fan not engage after the engine heats up in a 1986 Toyota Celica gt The fuse and relay are good. Unplugging the sensor the fan does not start but runs when wired to the battery.?

Answer 1

Try turing on the A/C to see if it works at all through the computer (just a quick easy test). You could have a coolant temperature sensor that has gone bad. On your car, I believe it's underneath the driver side of the valve cover, in the water outlet. The part is probably around 15 to 20 dollars. One other problem I've seen is the plug-in going into the fan coming out while running (many years of vibrations wearing out plastic connectors, who would've guessed?)