|LANCE’S CORNER – AUTO REPAIR HELP|
HEATER & A/C BLOWER MOTOR
Operation of the blower motor is controlled by a switch mounted in the HVAC control panel. The switch has multiple speed settings that control voltage supplied to the blower motor. Low and medium speeds are made possible by causing current to flow through the blower motor resistor assembly. The blower motor resistor contains different current paths that allow changing voltage levels to the blower motor. A low voltage will cause a low blower speed. Correspondingly higher voltages are supplied to the blower motor to make medium speeds possible. High speed is normally obtained by supplying full battery voltage to the blower motor through use of a blower relay. The blower motor relay is activated by the blower switch. When the blower switch is placed in the high position, a voltage signal is sent to the relay causing the contacts in the relay to close, sending full voltage to the blower motor.