Chart 1C-2 Blower Motor Runs All of the Time or High Speed Only

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

Blower motor speed is determined by the amount of voltage applied to the blower motor. This voltage varies from approximately 4 volts (low speed) to approximately 12 volts (high speed).

The speed at which the blower motor operates is governed by the H-A/C control. The blower motor speed can be adjusted manually by pressing the blower control "UP" or "DOWN" switches or automatically by placing the H-A/C control in the AUTO" mode.

The H-A/C control sends blower request information to the blower motor control module in the form of a variable voltage signal. This voltage signal ranges from approximately 2.5 volts, for minimum blower speed, to approximately 7 volts, for maximum blower speed. An amplifier and driver circuit in the blower motor control module supplies between 4 and 12 volts to the blower motor according to the request signal from the H-A/C control. Blower motor voltage is also sent back to the H-A/C control to insure blower speed stability and to indicate any failure in the blower motor circuitry.