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Function and Test Method of Engine Coolant Thermal Switches

Function and Test Method of Engine Coolant Thermal Switches

The temperature control switch is also called the thermal switch. The function of the coolant temperature thermal switches is to automatically switch on and off the fan motor power circuit according to the temperature of the coolant.


The detection method of the coolant temperature thermal switches:


When checking whether the temperature control switch is working properly, the temperature control switch should be removed and put into the water. Use the electric barrier of a multimeter to connect the two stylus to the limit end and the outer shell of the temperature control switch respectively. When the coolant temperature is lower than 87 At +2°C, the pointer of the multimeter should indicate disconnection, that is, the resistance is infinite. Change the coolant temperature: when the coolant temperature reaches 92+2℃, the pointer of the multimeter will indicate a certain resistance value. Otherwise, the temperature control switch is damaged and should be replaced.


What happens if the engine thermal switch is broken:


Both the water temperature sensor and the thermal switches monitor the water temperature of the engine. The water temperature sensor feeds the water temperature back to the computer and then sends the signal to the temperature control to control the fan's high and low speed operation. When one of them is damaged, the water temperature will be too high.


Generally, the water temperature collection signal is divided into two groups, but the current car 2 water temperature signals are all transmitted to the ECU, respectively, the ECU monitors the engine water temperature to adjust the mixture concentration in a timely manner, and the other does not participate in the engine work, but the ECU judges the water temperature by this signal, and then controls the cooling fan relay in time to make the cooling fan work and cool down. According to different models, some of the 2 water temperature sensors are independent, and some are 2 integrated into a whole to output 4 wires. The former is broken and has little to do with the high water temperature, but the high fuel consumption is not easy to start in cold weather or the hot car does not start well. If the latter is broken, the heating fan turns on and the temperature increases or the fan does not work at all.

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