Blower Motor Switch: Description and Operation

The A/C Heater blower motor is controlled by a rotary-type blower motor switch, mounted in the A/C Heater control panel On vehicles with manual temperature control systems, the switch allows the selection of four blower motor speeds, but will only operate with the ignition switch in the ON position and the A/C Heater mode control switch in any position, except OFF. On vehicles with the Automatic Zone Control (AZC) systems, the switch allows the selection of Lo Auto, Hi Auto, and ten speed settings between Lo and Hi.

On manual temperature control systems, the blower motor switch is connected in series with the blower motor ground path through the a/c heater mode control switch. The blower motor switch directs this ground path to the blower motor through the blower motor resistor wires, or directly to the blower motor, as required to achieve the selected blower motor speed.

On AZC systems, the blower motor switch is just one of many inputs to the AZC control module. In the manual blower modes, the AZC control module adjusts the blower motor speed through the blower motor controller as required to achieve the selected blower switch position. In the auto blower modes, the AZC control assembly is programmed to select and adjust the blower motor speed through the blower motor controller as required to achieve and maintain the selected comfort level.

The blower motor switch cannot be repaired and, if faulty or damaged, it must be replaced. The switch is serviced only as a part of the a/c heater control assembly.