What are the symptoms of a damaged car cooling fan resistor?

[DiCayden]

The blower resistor mainly controls the speed of the blower. If the blower resistor is damaged, the blower will operate at the same speed across all gear settings. Once the blower resistor fails, the air volume control knob loses its speed adjustment function. Here are the specific details about car air conditioning: 1. Introduction: The car air conditioning system, abbreviated as car AC, is used to regulate and control the temperature, humidity, air cleanliness, and airflow inside the car cabin to optimal conditions. It provides a comfortable riding environment for passengers, reduces travel fatigue, and creates favorable working conditions for the driver, playing a crucial role in ensuring safe driving. 2. AC Layout: Different types of AC systems have varying layouts. Currently, integrated heating and cooling AC systems are widely used in passenger cars. The layout involves assembling components such as the evaporator, heater radiator, centrifugal blower, and control mechanism together, referred to as the AC unit assembly.

[DeEdward]

Last time I was driving, I noticed an issue with the cooling fan. Once the fan started, it would only spin at high speed like a top and wouldn't stop. At first, I didn't pay much attention, but later the engine bay became extremely hot, and the dashboard warning light came on—that's when I realized it was serious. The resistor controls the fan speed, and when it fails, the fan can't switch to low-speed mode. It becomes noisy, consumes more power, and fails to lower the temperature, which can easily lead to engine overheating or even a blown head gasket. I tried touching the fan connector myself—it was scorching hot. Later, I took it to a mechanic, who said resistor failures are quite common, often caused by aging wiring or voltage instability. If left unrepaired for a long time, the air conditioning can also be affected, losing its cooling capability. Eventually, you'd have to replace the part, or driving in summer would be pure misery.

[StMason]

The most obvious symptom of a failing cooling fan resistor is the fan becoming uncontrollable: it either spins excessively fast with loud noise or stops working altogether. I've experienced this several times where the fan only operated at high speed, triggering the overheating warning light and causing the engine coolant temperature to soar alarmingly. This resistor controls the fan speed, and once damaged, the fan loses its low-speed adjustment capability, which over time leads to reduced cooling system efficiency and poor air conditioning performance. During inspection, you can test by feeling the temperature; a surge of hot air indicates the problem. Timely repair is crucial, as prolonged high temperatures can wear engine components, ultimately resulting in higher repair costs. Regular vehicle owners should periodically check the fan's operation and not wait for major issues to take action.

[BenjaminLynn]

If the resistor fails, the cooling fan will malfunction. I've seen cases where the fan either runs at full speed with a piercing noise or completely stops working, causing the engine overheating warning light to flash constantly. If it only runs at high speed without low speed, the water temperature rises rapidly; a complete failure poses even greater risks, especially in traffic jams where accidents are more likely to occur. If you notice the problem, it's best to get it repaired quickly to avoid compromising safety.