Symptoms of a Faulty Radiator Fan Resistor?
3 Answers
The main symptom of a faulty car cooling fan resistor is that the cooling fan runs continuously without adjusting its speed based on the engine coolant temperature. Prolonged high-speed operation can affect the lifespan of the cooling fan, while prolonged low-speed operation may lead to excessively high coolant temperatures, failing to cool the engine promptly and potentially causing engine damage. Therefore, a faulty cooling fan resistor should be replaced immediately. Below is a detailed introduction to the car radiator fan: Automatic activation conditions: The radiator fan automatically turns on when the coolant temperature reaches 98°C. The car radiator fan activates automatically and cannot be manually controlled; it does not start at low temperatures, and operates at two speed levels for medium and high temperatures. Radiator fan speed levels: Typically, the medium speed activates at 95°C, and the high speed activates at 105°C. When the coolant temperature reaches 95°C, the fan starts and runs at 1600 RPM. When the temperature reaches 105°C, the fan speed increases to approximately 2400 RPM to enhance cooling efficiency.
The symptoms of a faulty radiator fan resistor, which I've experienced several times. The most common issue is the failure of fan speed regulation. Normally, the fan should switch between high and low speeds to meet temperature demands. When it's broken, the fan either runs continuously at high speed with excessive noise, like racing on a highway, or only operates at low speed or even stops, causing the engine temperature to rise. The air conditioning cooling is also affected, making the air blown into the car not cool enough, which is really uncomfortable during hot weather. If the engine overheating warning light comes on, the resistor might be severely damaged. When checking the fan operation, if it starts at high speed and can't switch speeds, it's almost certain the resistor is faulty. In older cars, resistors are prone to aging, and factors like moisture ingress or unstable voltage can accelerate the damage. It's important to address the issue promptly once discovered to prevent engine damage due to insufficient cooling.
The radiator fan resistor is a key component that controls the fan speed. If it fails, the fan cannot automatically adjust based on the coolant temperature. Typical symptoms include restricted fan operation: it may only run at high speed, making loud noises, or only at low speed, failing to provide adequate cooling. The air conditioning may stop cooling due to insufficient pressure in the refrigeration system. The engine temperature rises quickly, with the gauge showing higher-than-normal readings or even triggering a warning light. Common causes of resistor failure include aging, short circuits, or connection issues. If the fan noise remains constant while driving, it's a warning sign. Testing the resistor's resistance or checking it with a multimeter can diagnose the problem. Prompt repairs can prevent overheating incidents.
