The working principle of automotive electronic fan
The electronic fan of the car monitors the water temperature through temperature controllers and sensors, and automatically starts or stops when it reaches a set threshold, while being affected by the air conditioning system. Its core working principle can be divided into the following points:
Temperature control mechanism
The start and stop of the electronic fan is controlled by the water temperature sensor and the temperature controller. When the coolant temperature reaches the preset upper limit (such as 90°C or 95°C), the thermostat triggers the electronic fan to operate at low or high speed; Stop working when the temperature drops to the lower limit.
Some models use two-stage speed control: 90°C at low speed, 95°C to switch to high-speed operation, in order to cope with different heat dissipation needs.
Air conditioning system linkage
When the air conditioner is turned on, the electronic fan automatically starts according to the temperature of the condenser and the refrigerant pressure, helping to dissipate heat and maintain the efficiency of the air conditioner. For example, when the air conditioner is running, the high temperature of the condenser may cause the continuous operation of the electronic fan.
Energy optimization design
The use of silicone oil clutch or electromagnetic clutch technology, only when the need for heat dissipation to drive the fan, reduce engine energy loss. The former relies on the thermal expansion of silicone oil to drive the fan, and the latter works through the electromagnetic suction principle.
typical fault scenario : If the electronic fan does not rotate, the load capacity of the motor may be reduced due to insufficient lubrication, aging, or capacitor failure. You need to check the temperature control switch, power supply circuit, and motor status. For example, sleeve wear will increase the internal resistance of the motor, affecting the efficiency of heat dissipation.
Common reasons for automotive electronic fan failure include substandard water temperature, relay/fuse failure, temperature control switch damage, fan motor damage, etc., which can be solved by targeted maintenance or replacement of parts.
The main reasons and solutions
Water temperature below start-up condition
The fan usually starts automatically when the engine water temperature reaches about 90-105 ° C. If the water temperature is not up to standard, the electronic fan does not turn is a normal phenomenon and does not need to be handled.
Relay or fuse failure
relay fault : If the electronic fan cannot be started and the water temperature is normal, check whether the relay is damaged. The solution is to replace a new relay.
blown fuse : Check the fuse box (usually a green fuse) under the steering wheel or near the glove box. If burned, should immediately replace the same size fuse, do not use copper wire/iron wire instead of , and repair as soon as possible.
The temperature switch/sensor is damaged
Diagnosis method : turn off the engine, turn on the ignition switch and air conditioning A/C, and observe whether the electronic fan rotates. If it is rotated, the temperature control switch is faulty and needs to be replaced.
Temporary solution : The temperature control switch plug can be short-connected with the wire with wire cover to force the electronic fan to operate at high speed, and then repair as soon as possible.
fan motor fault
If the above components are normal, test the electronic fan motor for stagnation, burning or poor lubrication. The motor can be directly driven by the external battery power supply, and the assembly needs to be replaced if it cannot operate.
Problem with thermostat or water pump
Inadequate thermostat opening can cause slow coolant circulation, possibly triggering high temperatures at low speeds. Check and adjust or replace the thermostat.
Water pump idling (such as Jetta avant-garde model plastic impeller cracking) need to replace the water pump.
Other notes
circuit check : If the electronic fan continues to rotate or the speed is abnormal, check the oil temperature sensor, rail circuit and control module.
Handling abnormal noise : abnormal noise may be caused by fan blade deformation, bearing damage, or foreign matter stuck. Clean or replace the corresponding parts.
It is recommended that the OBD diagnostic instrument read the fault code to assist the judgment. Complex problems need to be handled by professional technicians.
If you want to know more, keep reading the other articles on this site!
Please call us if you need such products.
Zhuo Meng Shanghai Auto Co., Ltd. is committed to selling MG&750 auto parts welcome to buy.
