What are the symptoms of a faulty car cooling fan resistor?
2 Answers
If the blower resistor is damaged, the blower will operate at the same speed across all settings. Once the blower resistor fails, the airflow control knob loses its speed regulation function. Below is relevant information: 1. Automotive air conditioning principle: The working principle of car air conditioning is actually quite simple. During heating, high-temperature coolant from the engine flows through the heater core. This allows the heater core to warm the air delivered by the blower, enabling the air vents to blow warm air. 2. Precautions: When cleaning the air conditioning system, avoid using low-quality foam cleaners as they may damage the blower. The blower contains a bearing - if this bearing lacks lubrication, it will produce abnormal noises during operation.
The cooling fan resistor failed. Initially, I noticed that when the car's AC was on, the fan would either spin at high speed continuously or not work at all. The engine temperature gauge fluctuated wildly, and sometimes the coolant temperature warning light would come on when stopped at a red light, scaring me into pulling over. It was more noticeable in city traffic—the hood got hot, and the AC didn’t blow cold enough. Upon inspection, the fan only had two states: either super quiet but ineffective or so loud it made my ears ring. Prolonged use like this can easily damage the engine. I recommend going to a repair shop immediately to check the resistor and fan control module—after replacement, everything worked fine. Don’t delay; overheating is dangerous on highways and wastes fuel. Regularly cleaning dust buildup around the fan can prevent similar issues.
