Heater Blower Motor Switch Resistor

The heater blower motor (18527) speed is controlled by a four-position switch:

• LO
• MEDIUM LO
• MEDIUM HI
• HI

It is identified by the pictograph FAN on the face of the heater control (18549) assembly. Its purpose is to provide a current path through or around the resistor coils in the heater blower motor switch resistor (18591) assembly so that the desired heater blower motor speed will be obtained.

Heater Blower Motor Switch Resistor

• With the blower motor switch (19986) in the LO position, current flow to the A/C blower motor is restricted by the three resistor coils in the heater blower motor switch resistor assembly.
• When the blower motor switch is moved to the MEDIUM LO position, one of the resistor coils is bypassed and current flow to the A/C blower motor is restricted by only two resistors.
• In the MEDIUM HI position, two resistor coils are bypassed and current flow to the A/C blower motor is restricted by only one resistor.
• In the HI position, the blower motor switch provides a current path around all resistors and full current (power) is available for the A/C blower motor to operate at full speed.