Air Speed - Auxiliary

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

There are 2 separate operator controls for the auxiliary HVAC system. There is the front auxiliary HVAC control assembly and the RSA control module. If the front auxiliary blower motor switch is in the AUX. position, then the system will only function with inputs to the front auxiliary HVAC control assembly. If the front auxiliary blower motor switch is in the OFF position, then the RSA control module does not respond to input. The auxiliary HVAC control module can not request A/C operation from the PCM. A rocker type switch on the RSA control module provides the operator the ability to select several blower speeds. The RSA control module uses a bar graph to indicate the selected blower speed. The auxiliary blower motor control processor supplies a 5 V reference to the auxiliary HVAC control module on the auxiliary blower motor speed control circuit. The auxiliary HVAC control module pulls the 5 V reference low towards ground to provide a blower motor speed signal. As the voltage decreases the blower speed increases. Power and ground are provided to the auxiliary blower motor control processor through the battery positive voltage and ground circuits.