Front Blower Motor Controls

The Front Heater and A/C functions are controlled by the HVAC Control Module which include a Mode Switch, Fan Switch and a Temperature Control Motor. Battery voltage is provided to the controls by HTR-A/C Fuse (Fuse 12). High Speed Blower Voltage is provided by the A/C MAXI FUSE (Fuse M3). This voltage is provided directly to the Blower Motor when the Blower Relay is energized. This Relay is located in the lit lower Motor Resistor and Relay Pack.

The Blower Speed is controlled by the Fan Switch in conjunction with the Mode Switch. Voltage from BRN 141 wire is passed through the Mode Switch and on to the Fan Switch for all Mode settings except OFF. When the Fan switch is in the HIGH position, battery voltage is provided to the Blower Motor Resistor and Relay Pack, through the A/C MAXI Fuse M3 and the RED (542) wire. The BLK (350) wire cavity C provides a ground for the coil of the Blower High Speed Relay as well as the Front Blower Motor When this Relay is energized, it completes the circuit to the Front Blower Motor bypassing the resistor pack and will operate the Blower Motor at High speed.

The slower Blower Motor speeds are accomplished by limiting the current to the Blower Motor by increasing the resistance. When the M2 setting is selected, a current path is provided through cavity F of the Blower Motor Resistor and Relay Pack, through the selected Resistor and the normally closed contacts of the High Speed Blower Relay and to the Front Blower Motor. This circuit puts one Resistor in the circuit. When an even lower speed is desired, the Fan Switch is placed in the M1 position. This provides a current path through the switch to the TAN (63) wire cavity D of the Blower Motor Resistor and Relay Pack. This places two resistors in the circuit, thus reducing the current flow to the Front Blower Motor and reducing the Blower Motor speed.
The slowest Blower Speed is accomplished by placing three resistors in the circuit. This is accomplished when the LOW setting is selected from the Fan Switch. Current flows through YEL (60) wire cavity E of the Blower Motor Resistor and Relay Pack, through the selected resistors and the normally closed contacts of the High Speed Blower Relay to the Front Blower Motor. This places three resistors in the circuit, thus reducing the current flow to the Front Blower Motor and reducing the Blower Motor speed.