In a blower motor, the relay supplies the power that allows the fans to circulate warmed air. Essentially an on/off switch, the blower motor relay’s reactions start and end the heating process in HVAC systems by controlling the flow of current between the power source and the motor.
What causes a resistor to go bad?
A fixed composition resistor normally fails in an open configuration when overheated or overly stressed due to shock or vibration. Excessive humidity may cause an increase in resistance. A variable composition resistor may wear after extensive use, and worn away particles may cause high resistance short circuits.
Can you bypass a blower motor resistor?
Bypassing the resistors should run the fan on high speed. High speed requires more DC current, so high speed was fed through a relay and heavier wire to prevent the wire from burning up.