The function of the automotive electronic fan
The automotive electronic fan is a key component of the vehicle's cooling system, primarily functioning to help maintain an appropriate operating temperature for the engine and related components, ensuring the vehicle operates efficiently and safely.
The core function of the electronic fan is to dissipate heat. It does this by forcing air to flow over the radiator (water tank) to cool the hot engine coolant, preventing the engine from overheating. It is usually controlled by a water temperature sensor or a temperature control switch. When the coolant temperature reaches a set threshold (such as 90°C or 95°C), it automatically starts, stops when the temperature drops, achieving energy conservation and efficient management.
In addition, the electronic fan supports the operation of the air conditioning system. In cooling or heating modes, it drives air to pass through the air conditioning condenser or evaporator to enhance cooling efficiency or distribute hot air, thereby regulating the interior temperature.
The intelligent control of the electronic fan brings several advantages, including optimizing energy consumption through speed adjustment (such as high and low speed modes), reducing engine load, and compensating for insufficient natural ventilation at low speeds or idling, ensuring the cooling effect.
Troubleshooting the failure of the electronic fan not rotating requires a step-by-step approach: First, check if the water temperature is within the standard range (normal startup temperature is approximately 90-95°C). Then, test the fuses, relays, temperature control switch, and motor in sequence. Here is a systematic troubleshooting process:
Basic inspection (priority operation)
Water temperature detection: Start the engine to reach the normal operating temperature (about 10 minutes), observe the water temperature gauge on the dashboard. If the water temperature is below 90°C, the fan not rotating is a normal phenomenon; if the water temperature is within the standard range but still does not rotate, further investigation is required.
Fuse inspection: Open the engine compartment fuse box, find the fan fuse (refer to the vehicle manual for location), use a multimeter to test if it is blown. If blown, replace it with the same specification fuse (do not use copper wire as a substitute).
Core component inspection
Relay test:
Start the vehicle and turn on the A/C switch. Listen for a "click" sound from the relay.
If there is no sound, use a multimeter to detect the resistance of the relay coil (normal value 50-100Ω). If abnormal, replace it.
Temperature control switch verification:
Unplug the temperature control switch plug and short-circuit the pins. If the fan rotates, the switch is damaged and needs to be replaced.
If it does not rotate, check if the switch circuit is open (test with a multimeter for continuity).
Deep fault handling
Motor diagnosis:
Disconnect the power supply and manually move the fan blades. If there is a jam or abnormal noise, lubricate the rotating shaft (drip a special lubricating oil) or replace the motor.
Power-on test of the motor: Connect a 12V power supply, if it does not rotate, it is a motor fault.
Circuit and sensors:
Check the fault codes of the ECU (vehicle computer) using an OBD-II reader.
Test the resistance of the water temperature sensor (at normal temperature, approximately 200-500Ω), if the value is abnormal, replace it.
When the electronic fan of the vehicle is broken, it can cause phenomena such as engine overheating, water tank leakage, and abnormal fan operation. The specific manifestations include the engine temperature soaring, failure of the cooling system, and physical damage to the fan. The following is a detailed description of the phenomenon classification:
Engine cooling system malfunction
The electronic fan failure directly affects the cooling efficiency, leading to a chain reaction:
Engine temperature rises sharply: After the fan stops rotating, the heat in the water tank cannot be dissipated, the temperature gauge pointer rises rapidly (usually exceeding 95°C), the dashboard water temperature warning light turns on, which may cause power loss or engine shutdown.
Water tank rupture or leakage: High temperature causes the pressure in the water tank to increase sharply, the water tank bursts or the seal fails, and cooling fluid stains the ground. The water circulation is blocked, further exacerbating engine overheating.
Severe engine damage: Continuous high temperature causes "slip-on cylinder" (coolant splashes into the cylinder), resulting in piston jamming, lubrication failure, and ultimately requiring major repair or engine replacement.
Indicators of the electronic fan's own failure
These can be detected through direct observation or operation:
Burn marks and odors: The motor ventilation port coil turns black and emits a smell of plastic burning or wire short-circuiting.
Slow or stopped rotation: It is difficult to manually rotate the shaft, and the movement is not smooth (the bearing lacks oil or the rotor is out of alignment).
No fan operation sound in the engine compartment, or no wind sensation upon touch.
Abnormal temperature: The surface temperature of the fan rises too quickly (it feels hot for a short time), indicating an internal short circuit.
Other associated effects
Air conditioning cooling failure: Insufficient heat dissipation leads to excessively high pressure in the high-pressure pipe of the air conditioner, resulting in poor cooling effect or even pipe rupture.
Abnormal noise: The motor gets stuck and makes friction sounds or high-frequency abnormal noises.
Warning: When the water temperature reaches above 80℃, the fan should automatically start. If it does not rotate, it needs to be repaired immediately to avoid engine damage.
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