F 150 2WD V8-5.4L Flex Fuel (2008)
Blower Motor Resistor: Description and Operation
BLOWER MOTOR RESISTOR
The blower motor resistor adjusts the blower motor speed based on the blower motor switch setting. The blower motor resistor contains 3 resistor coils
in series. The end of each resistor coil is wired to a setting in the blower motor switch. Voltage from the blower motor relay is available at the blower
motor at all times when the blower selector is in an ON position, and then continues to the blower motor resistor. The blower motor switch will allow a
path to ground with the addition of 1, 2 or 3 coils in the blower motor resistor to the circuit. When the blower motor switch is in the MED HI position,
the blower motor switch will add a path to ground through one coil in the blower motor resistor. When the blower motor switch is in the MED LO
position, the blower motor switch will add a path to ground through 2 coils (in series) in the blower motor resistor. When the blower motor switch is in
the LO position, the blower motor switch will add a path to ground through 3 coils (in series) in the blower motor resistor. When the blower motor
switch is in the HI position, the blower motor resistor is bypassed.
