Blower Motor Relay: Description and Operation

Variable Blower Controller/High Blower Relay (VBC):

The solid state Variable Blower Controller/high Blower Relay (VBC) converts low current signals from the Automatic Temperature Control (ATC) module to a high current, variable ground feed to the blower motor. The blower motor speed is infinitely variable and is controlled by the ATC control module software. A delay function provides a gradual increase or decrease in the blower motor speed under all conditions. When the ATC control module signals the VBC to maximum blower speed, a relay bypasses the solid state control and provides a direct path to ground for the blower motor.

CAUTION: The system should not be operated with the blower motor disconnected. Damage may occur to the VBC if cooling air is not provided through the evaporator assembly.