What faults will occur if the car fan resistor is broken?
2 Answers
The blower resistor mainly controls the speed of the blower. If the blower resistor is broken, the blower speed will remain the same across all gear positions. Once the blower resistor fails, the air volume control knob loses its speed regulation function. Here is some relevant information: Blower: The blower is a crucial component in the car's air conditioning system and is also one of the most prone to failure. Car Air Conditioning: Whether heating or cooling, the car air conditioning system relies on the blower. The principle of car air conditioning is 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.
During that long-distance trip, I encountered a fan resistor failure. When I turned on the AC, the fan didn't spin at all, making the car as hot as a steamer. After stopping to check, the engine was alarmingly hot, and the dashboard temperature warning light stayed on. The mechanic told me the resistor controls the fan speed—when it fails, the fan either gets stuck or runs at high speed, disrupting the cooling system and risking engine overheating. I rushed to the shop to replace the resistor, which fixed the issue. Now, I always check if the fan runs properly at startup. Don’t underestimate it—if it fails, the AC stops working and fuel efficiency drops. Early repairs prevent costly roadside breakdowns. Always monitor engine temperature during highway driving and pull over immediately if anything seems off.
