Grand Cherokee 2WD L6-4.0L VIN S (1997)
Blower Motor Switch: Description and Operation
The content of this article reflects changes called for in TSB 26-12-96.
BLOWER MOTOR SWITCH
The heater-A/C blower motor is controlled by a rotary 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 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 controller. In the manual blower modes, the ATC controller adjusts the
blower motor speed through the power module or the high speed blower motor relay as required by 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 power module or the high speed blower motor
relay 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.
