* High Engine Coolant Temperature: This is the most common and normal reason. The engine coolant temperature sensor detects when the coolant is getting too hot and signals the fan to turn on to cool it down. This is perfectly normal operation. Check your coolant level; low coolant can lead to overheating and thus fan activation.
* Faulty Coolant Temperature Sensor (CTS): If the CTS is malfunctioning, it might be sending a false signal to the PCM (Powertrain Control Module) indicating high coolant temperature, even if the engine isn't actually overheating. This will cause the fan to run unnecessarily.
* Faulty Radiator Fan Relay: This relay acts as a switch for the fan. A faulty relay can cause the fan to run continuously or not at all.
* Faulty Radiator Fan Motor: The fan motor itself could be short-circuiting, causing it to run constantly.
* Faulty PCM (Powertrain Control Module): While less common, a problem with the PCM can cause incorrect signals to be sent to the fan, leading to continuous operation. This is usually accompanied by other symptoms.
* AC System Operation: The radiator fan often runs to assist the AC condenser in cooling the refrigerant. If your AC is on, the fan should run. This is normal.
Troubleshooting Steps:
1. Check Coolant Level: Make sure your coolant level is within the normal range in the overflow reservoir. Low coolant will cause overheating and fan operation.
2. Check Engine Temperature: Observe your temperature gauge. If it's consistently reading high, you have an overheating issue.
3. Listen to When the Fan Turns On: Does it only run when the engine is hot or when the AC is on? Or does it run even when the engine is cold? This will help narrow down the possibilities.
4. Inspect the Radiator Fan and Shroud: Check for any obvious signs of damage or debris obstructing the fan blades.
5. Check the Radiator Fan Relay: Locate the relay (usually in the fuse box under the hood) and try swapping it with a relay of the same amperage rating from another circuit (if possible and safe). If the problem follows the relay, replace it.
6. Test the Coolant Temperature Sensor: This requires a multimeter and a bit of automotive knowledge. There are many online tutorials demonstrating how to test a CTS.
7. Professional Diagnosis: If you're uncomfortable performing these tests, take your Caravan to a qualified mechanic for diagnosis and repair.
The key is to determine *when* the fan is running. If it's only running when the engine is hot (and the gauge shows high temperature) it might be normal. If it runs constantly, even when the engine is cold, you've got a problem that needs investigation.
