A/C Blower Motor Resistor

A/C blower motor speed is controlled by a four-position switch:

• LO
• MEDIUM LO
• MEDIUM HI
• HI

The switch is identified by the pictograph FAN on the face of the air conditioner control (19980) assembly. Its purpose is to provide a current path through or around the resistor coils in the A/C blower motor resistor assembly, so that the desired A/C blower motor speed will be obtained.

• With the switch (19986) in the LO position, current flow to the A/C blower motor is restricted by the three resistor coils in the A/C 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.

NOTE: Current flows through the thermal limiter in all A/C blower motor switch positions. The thermal limiter will open at 121°C (250°F) and the A/C blower motor switch resistor assembly must be replaced if the thermal limiter opens.