Symptom: Idle running time is too long engine will be "boil", while the instrument in the high temperature warning light.
    Trouble check: parking check found that the electronic fan does not run. Users said the car due to high temperature engine failure has repeatedly repaired, had changed several temperature control switch, the first replacement after troubleshooting, but not long before the failure to reproduce. And then replace the temperature control switch to no avail. It is now connected to the temporary control line, with manual switch in the cab according to the instructions of the coolant thermometer for artificial control.
    Open the machine cover after the first pull out the temperature control switch plug, with a short connection were connected to the circuit 1, 3 and 1 and 2 jack, open the ignition switch to "ON" block, found that electronic fan only high speed No low speed, with the infrared thermometer on the water pipe to test and found that the coolant temperature is basically the same, indicating that the engine cooling cycle system is normal. It seems that the fault is still in the electronic fan. Car repair home
    And then use the infrared thermometer to measure the temperature around the temperature control switch wall temperature, at 95 ℃ or so, and measure the temperature control switch copper parts, the temperature is not so high, indicating the temperature control switch feel the temperature and the temperature of the coolant itself Inconsistent. Suspected temperature control switch sensor plug may exist around the foreign body, then remove the temperature control switch and found that the installation hole is not outflow antifreeze. With a screwdriver poke the mounting hole, suddenly a coolant from the hole out and fall out of a scale, the problem suddenly see the light. The temperature control switch on the inside of the installation hole cleaning, fitted with the original temperature control switch, re-filling antifreeze test, everything is normal.
    Check the results: According to the user said that the car has traveled 150,000 km, winter with antifreeze, summer with tap water. As the temperature control switch sensor plug for the copper, easy to scale, slowly in the temperature control switch around the formation of the scale layer, and scale heat transfer capacity is very poor, so the temperature control switch feel the temperature is always more than The coolant temperature is low, so that when the engine coolant temperature is already high, the electronic fan does not work.