What Causes the Failure of the Mercedes Blower Regulator?

[McKate]

Possible causes include a damaged blower or issues with the connection of power wires, sensor wires, and fan wires to the thermostat. The car blower's function is to direct the cold air from the air conditioning evaporator or the hot air from the heater core into the vehicle interior. Simply put, the blower serves to circulate air. Below is an introduction to the control principles of the blower: 1. Automatic Control: When the "Auto" switch on the air conditioning control panel is pressed, the air conditioning computer automatically adjusts the blower speed according to the required air temperature output. When the airflow direction is set to "Face" or "Bi-Level" and the blower is in low-speed mode, the blower speed will vary within a defined range based on the intensity of sunlight. 2. Low-Speed Control Operation: During low-speed control, the air conditioning computer cuts off the base voltage of the power transistor, which in turn disconnects the power transistor and the high-speed relay. Current flows from the blower motor to the blower resistor and then to ground, causing the motor to operate at low speed.