Electrical System

The electrical system consists of the blower motor (18527), heater blower motor switch (18578), heater blower motor switch resistor (18591) with a thermal limiter, A/C cycling switch (19E561), A/C clutch (2884) and the fuse and wiring to complete the circuits.

The blower motor is installed in the A/C blower housing (19930), which is part of the A/C evaporator housing (19850). The blower motor is connected to the electrical circuit with one hardshell connector located near the blower motor.

The heater blower motor switch is installed on the A/C control (19980) and, when used with the heater blower motor switch resistor, provides the selection of four operating speeds.

The heater blower motor switch resistor is installed in the A/C evaporator case (19897) between the blower motor and the A/C evaporator core (19860).

The heater blower motor switch resistor also contains a thermal limiter that is used as a temperature-protecting fuse. The thermal limiter is located a preset distance from the resistor coils. If the temperature of the thermal limiter reaches approximately 121°C (250°F), the limiter contacts will open, interrupting the circuit for all speeds except high speed. The thermal limiter will not reset so the heater blower motor switch resistor must be replaced if the thermal limiter opens.

The A/C cycling switch is located on the side of the suction accumulator/drier (19C836) and controls cycling of the A/C clutch. When the pressure increases to approximately 276-324 kPa (40-47 psi), the A/C cycling switch closes. When the pressure drops below approximately 163-175 kPa (23.5-25.5 psi), the A/C cycling switch opens to stop compressor operation. In ambient temperatures below approximately 7°-10°C (45°-50°F), the A/C cycling switch will not allow compressor operation because the switch will open due to low system pressures.