2002 Buick Lesabre Blower Motor

The 2002 Buick Lesabre blower motor at times does not come on and then will start blowing or at other times the blower motor won’t come on for a long while but will sometimes start blowing after a restart.

RESPONSE

This is form loose wiring, bad wiring connection or failing blower motor. Most common would be a failing blower motor. The blower motor has internal brushes that wear and begin to make weak contact. Replacing the motor should take care of the issue.

The 2002 Buick Lesabre Blower motor Replacement without Vent Tube

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The 2002 Buick Lesabre Blower Motor Replacement with Vent Tube

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The 2002 Buick Lesabre Blower Motor Control Processor

The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive voltage and ground circuits enable the control processor to operate. The HVAC control module provides a PWM signal to the control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower motor voltage supply circuit. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.

Air Speed

The blower motor forces air to circulate within the vehicle’s interior. The vehicle operator determines the blower motor’s speed by placing the blower motor switch in a desired speed position or by selecting automatic operation. The blower motor will only operate if the blower motor switch is in any position other than OFF, and the ignition switch is in the RUN position. In manual operation, once a blower speed is selected, the blower speed remains constant until a new speed is selected. In automatic operation, the HVAC control module will determine what blower speed is necessary in order to achieve or maintain a desired temperature.

As the requested blower speed increases, the following conditions occur:

•	The IPM increases the amount of time that the blower motor speed control circuit is modulated to ground.

•	The voltage and duty cycle, measured between the blower motor speed control circuit and ground, decrease.

As the requested blower speed decreases, the following conditions occur:

•	The IPM decreases the amount of time that the blower motor speed control circuit is modulated to ground.

•	The voltage and duty cycle, measured between the blower motor speed control circuit and ground, increase.