Oldsmobile/Buick Repair: 92 buick century fan, upper radiator hose, coolant recovery

Question
My 92 buick century keeps over heating. I found out the fan isnt coming on what is causing it to not come on?

Answer
Hello Misty,
The fan is operated by a relay, with power from a fusible link, probably located at the starter.
The relay is energized by the ECM, according to engine temperature signals from a temp sensor.
Any of those could be bad.

One way to test the fan itself is unplug it, and use jumper wires from the battery to see if the fan motor is good.

Find the relay, and swap it with another of the relays, to see if the relay is good. You can use a test light at the fan connections when the engine is hot to see if power is being sent to the motor.

If the engine is low on coolant...and I mean inside the radiator, not just looking at the coolant recovery tank, then the temp sensor would not be sending the correct signal, even though the engine is hot. The sensor depends on the sensor bulb being submerged. Be careful checking that one...don't remove the radiator cap when the engine is hot.   A tip here is, squeeze the upper radiator hose to see if it is under pressure before removing the cap.

Van