* Fan Motor Failure: The most common cause is a faulty fan motor itself. It may have burned out due to age, overheating, or electrical issues.
* Fan Relay Failure: The fan is controlled by a relay, an electrical switch. A bad relay prevents the fan from receiving power even if the engine is overheating.
* Wiring Problems: Worn or damaged wires leading to the fan motor or relay can interrupt the circuit, preventing the fan from operating. This includes connectors.
* Temperature Sensor Malfunction: The cooling system uses a temperature sensor to tell the engine control module (ECM) when to turn the fan on. A faulty sensor may not register high enough temperatures, thus not activating the fan.
* Fuse Blown: A blown fuse in the system's circuit will also stop the fan from working.
* Low Coolant: If the coolant level is low, the engine may overheat, but the fan might still work correctly because the problem is the lack of coolant, not the fan.
To troubleshoot:
1. Check the coolant level: Ensure the coolant is at the correct level. Low coolant is a serious issue regardless of fan function.
2. Check the fuse: Locate the fuse for the radiator fan in your vehicle's fuse box (consult your owner's manual).
3. Listen for the fan: With the engine running and at operating temperature, carefully listen for the fan to kick on.
4. Check the relay: You may need to test the relay with a multimeter or simply swap it with another relay of the same rating (again, consult your owner's manual).
5. Visual inspection: Look for any obvious damage to the fan, wiring, or connectors.
6. Advanced testing: If you're comfortable, testing the fan motor directly with a jumper wire and power source (carefully!) can determine if the motor is functioning correctly. However, this is dangerous and should only be done if you have electrical experience.
If you are not comfortable performing these checks, take your 90 Corsica to a mechanic for diagnosis and repair. An overheating engine can cause significant damage.
