Checking a radiator fan primarily involves verifying its motor's functionality and ensuring it activates when needed. The simplest method is to directly power the fan motor.
Here's a breakdown of how to test a radiator fan:
-
Visual Inspection:
- Before any electrical tests, visually inspect the fan for any physical damage. Look for cracks, broken blades, or debris obstructing the fan's movement.
- Check the wiring harness and connectors for any signs of damage, corrosion, or loose connections.
-
Direct Power Test:
- This test bypasses the vehicle's cooling system controls and directly powers the fan motor.
- Safety First: Disconnect the fan's electrical connector from the vehicle's wiring harness to isolate it. Ensure the vehicle is turned off.
- Jumper Wire Connection: Using two jumper wires, connect one wire to the positive (+) terminal of the vehicle's battery and the other to the negative (-) terminal.
- Fan Activation: Carefully touch the positive jumper wire to the positive terminal on the fan motor's connector (pigtail harness) and the negative jumper wire to the negative terminal.
- Observation:
- Successful Test: The fan should immediately turn on and spin at full speed, smoothly, and without any abnormal noises. This indicates the fan motor itself is functioning.
- Unsuccessful Test: If the fan doesn't turn on, either the fan motor is faulty or the jumper wires are not properly connected. Recheck your connections before concluding the motor is bad.
-
Check the Fan Relay (if applicable):
- Locate the radiator fan relay in the vehicle's fuse box. Consult your vehicle's repair manual for the location.
- Swap the radiator fan relay with an identical relay (e.g., the horn relay).
- Start the vehicle and allow it to warm up to operating temperature. If the fan now operates, the original relay is faulty and needs replacement.
-
Temperature Sensor/Switch (More Advanced):
- The radiator fan is often controlled by a temperature sensor or switch located in the radiator or engine block. This sensor tells the fan when to turn on based on the coolant temperature.
- Testing this sensor typically requires a multimeter and the vehicle's repair manual for specific resistance values at different temperatures. This is a more advanced diagnostic procedure.
In summary, the most direct way to check a radiator fan is to apply power directly to the fan motor using jumper wires. If the fan spins, the motor is likely good. If not, the motor is likely faulty.
