General Information

The blower motor forces ambient air into the vehicle's interior. The vehicle operator determines the blower motor's speed by toggling the blower motor switch manually or by using the automatic mode The blower motor will always operate at some speed as long as the HVAC control module is in any position other than OFF, as long as the ignition switch is in the RUN position.

Power is provided to the blower motor from the battery positive voltage circuit. Ground is provided by the ground circuit.

When a blower speed is selected manually, a signal is sent from the HVAC control module to the HVAC control processor on the class 2 serial data circuit. Once the signal is either received by the HVAC control processor or an automatic blower speed is determined by the processor, a signal is sent to the blower motor on the blower motor speed control circuit. The blower motor will then Pulse Width Modulate (PWM) the ground. When a low blower speed is requested, the PWM signal is reduced. When a higher blower speed is requested, the PWM signal is increased. In automatic operation, the HVAC control processor will determine what blower speed is necessary in order to achieve or maintain a desired temperature. Toggling the blower switch manually also activates the VF display for the blower speed selected. Whenever you service the blower motor, carefully handle the motor. The balance of the blower motor is very sensitive to handling.

When the vehicle operator toggles the blower motor switch, the blower can operate in either a manual, automatic or combination of the two modes. When the blower motor switch is toggled up one position, from the AUTO mode. The blower motor speed increases slightly and the HVAC control module displays HI AUTO. The fan operates automatically, similar to the automatic setting, except at a slightly faster blower speed.

When the blower motor switch is toggled up two positions, from the AUTO mode, the blower motor runs at a fixed speed and the HVAC control module displays HI. This is a complete override of the automatic blower system.

When the blower motor switch is toggled down one position, from the AUTO mode, the blower motor speed decreases slightly and the HVAC control module displays LO AUTO. The fan operates automatically, similar to the automatic setting, except at a slightly slower blower speed.

When the blower motor switch is toggled down two positions, from the AUTO mode, the blower motor runs at a fixed speed and the HVAC control module displays LO. This is a complete override of the automatic blower system.