Blower Motor Relay: Description and Operation

The blower relay makes it possible to apply battery voltage directly to the blower motor without using heavy gauge blower circuit wiring or a high current capacity blower switch.

When the blower switch is in LO, M1 or M2, the blower relay is de-energized. Current flows through the blower resistor assembly and the de-energized relay contacts to the blower motor. The blower motor runs at LO, M1 or M2 speed none of these speeds requires high current flow.

When the blower switch is in HI, current flows through the blower switch to the blower relay and energizes the relay coil. The relay contacts change position and current flows directly to the blower motor, through the energized relay contacts.