1. Electrical issues: Check the electrical connections to the heater fan motor. Make sure that they are clean and tight. You can also try wiggling the wires to see if the fan starts working. If it does, you may need to replace the connector or the wiring.
2. Faulty heater fan resistor: The heater fan resistor controls the speed of the fan. If it is faulty, it can cause the fan to work intermittently. To check the resistor, remove it from the vehicle and connect it directly to a power source. If the fan works, the resistor is faulty and needs to be replaced.
3. Faulty heater fan motor: If the heater fan motor is faulty, it can cause the fan to work intermittently. To test the motor, remove it from the vehicle and connect it directly to a power source. If the fan does not work, the motor is faulty and needs to be replaced.
4. Blockages: The heater fan can also be blocked by debris, such as leaves and dirt. This can prevent the fan from working properly. To check for blockages, remove the heater fan from the vehicle and inspect it. You can also use a vacuum cleaner to remove the debris.
If you are not comfortable troubleshooting and repairing your Mercedes C180 yourself, you can take it to a qualified mechanic.
