The second function is that the sensor is connected to the water temperature meter, which shows the temperature of the cooling water in the tank.
The Jetta has three wires. What's the smaller one?
The small one is the water temperature warning line. The temperature switch is installed on the air conditioner operating panel, and the temperature sensor is installed on the air conditioner air intake vent. The working principle of the temperature control switch: The temperature control switch is composed of a wax temperature driving element and a two-speed contact action mechanism, which uses the volume of the paraffin wax to suddenly increase when it is heated from solid to liquid to move the push rod and control the opening and closing of the contact. As the temperature of the coolant rises, the paraffin begins to expand, pushing the push rod through the rubber sealing film and overwhelming the spring frame. When the cooling water temperature rises to 95℃, the low-speed contact is closed, the radiator motor fan is switched on, and the operation is at a low speed of 1600rmin. When the cooling water temperature continues to rise to 105 ° C, the high-speed contact is closed because the paraffin continues to expand, so that the radiator motor fan runs at a high speed of 2400rmin to increase the cooling intensity.
The sensor on the car water tank is a water temperature sensor, which is used to transmit the cooling water temperature to the water temperature meter. Water temperature sensor and water tank with iron, there is a power line and water temperature meter connected, as the engine runs, the cooling water temperature will be higher and higher, the water temperature sensor on the water tank will continue to transfer the current temperature of the cooling water to the water temperature meter, displayed on the water temperature meter.