Grand Cherokee 4WD V8-5.2L VIN Y (1998)
Blower Motor Switch: Description and Operation
Blower Motor Switch
The heater-A/C blower motor is controlled by a rotary-type blower motor switch, mounted in the heater-A/C 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 heater-A/C mode control switch in any position, except Off. On vehicles with the Automatic Temperature Control (ATC)
systems, the switch allows the selection of Lo Auto, Hi Auto, and an infinite number of manual 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 heater-A/C
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 ATC systems, the blower motor switch is just one of many inputs to the ATC control module. In the manual blower modes, the ATC control
module adjusts the blower motor speed through the blower motor power module as required to achieve the selected blower switch position. In the
auto blower modes, the ATC controller is programmed to select and adjust the blower motor speed through the blower motor power module 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 heater-A/C
control assembly.
