Blower Motor Speed

The HVAC module controls the blower speed by sending a PWM signal to the blower motor speed control. The blower motor speed control provides variable ground feed for the blower motor to control the speed. A delay function provides a gradual increase or decrease in blower motor speed under all conditions.

The blower motor speed control has internal temperature and surge protection. In the event of excessive blower motor supply voltage or current draw, or if the blower motor speed control temperature climbs considerably due to a failure event (such as a seized or partially-seized blower motor), the blower motor speed control automatically shuts down the blower motor. After shutdown, the blower motor speed control attempts to restart every 120 seconds until the blower motor can be safely operated.