Introduction of automotive electronic fan circuit:
1. Fan relay If this line is broken, the fan will not have a low speed, and at the same time, only one fan will run at high speed. Short circuit to ground back causes the fan to run at low speed continuously. Short circuit to the positive pole causes damage to the temperature control box and the fan does not have a low speed. At the same time, only one fan runs at high speed.
2. Power supply: Opening of this line will cause the fan not to run. This line must be checked with a test light, to ensure that the test light can be bright. If there is only 12 voltages, but the test light cannot be made bright, then the fan system will not work properly.
3. Air conditioner switch signal: The circuit is open. When the air conditioner is turned on, the fan does not have a low speed, but the circuit controlled by the water temperature is normal. What I want to explain in particular about this line is that if the line is damaged or the plugs get into the water, it also causes leakage to the positive electrode. That is to say, if the air conditioner switch is not turned on, if a 2 volt induced voltage is generated on the line, it may cause the fan to run at a low speed without stopping.
4. Water temperature sensor circuit: These two lines are very sensitive to resistance and voltage. Even if there is very little water in the circuit, the fan will not work properly. The common situation is that the fan does not turn. If there is water in the water stability sensor plug, the fan will not work until the water is dry.
5. Fan relay: This line is to control two fan relays at the same time. The circuit break will cause the two fans to not have high speed. A short circuit to ground will cause a fan to always be high speed. A short circuit to the positive pole will damage the temperature control box.
6. Air conditioning cut off relay: cut off the air conditioner when the water temperature is too high. A short circuit to ground will cause the air conditioner to be cut off.
7. Air conditioning heavy load or high pressure signal, an important reminder: If the signal circuit has a small leakage to the positive electrode, it will cause the fan to run at high speed. Therefore, in addition to the test lamp test, a multimeter must also be used. With a voltage of more than 2 volts, the fan may continue to run at high speed.