Control Module HVAC: Description and Operation

Blower Motor Speed Control
The A/C blower motor speed control:
- is located on the A/C evaporator housing, in the engine compartment.
- converts low power signals from the dual automatic temperature control module to a high current, variable ground feed for the blower motor.
- varies the blower motor speed and is controlled by the DATC module software.
- provides a gradual increase or decrease in blower motor speed under all conditions by use of a delay function.

Rear Audio/Climate Control Module
The rear audio/climate control module is equipped on limousine (long wheel base) vehicles. The rear audio/climate control module converts an input from the rear audio/climate control switch, then signals the Audio Control Module (ACM) via the Audio Corporate Protocol (ACP) bus. The ACM then signals the DATC module over the J1850 communications network (Standard Corporate Protocol [SCP] bus).