Air Speed: Notes

WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

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 HVAC control module 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 HVAC control module 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.