Control Module HVAC: Description and Operation

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, Blower motor speed signal, battery positive voltage and ground circuits enable the control processor to operate. The HVAC control module sends the commanded blower motor speed to the control processor through a 0 to 12-volt linear ramped blower motor speed control circuit. As the blower motor speed control voltage increases, the blower motor speed increases. The control processor sends the actual blower speed to the control module through a 0 to 12-volt blower motor speed signal circuit. The processor supplies 12volts 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.