Electrical System

Electrical System

The components of the electrical system are the [1][2]blower motor relay, blower motor, a heater blower motor switch, a heater blower motor switch resistor with thermal limiter, an A/C cycling switch, a high pressure cut-off switch, an A/C clutch, and the fuse and wiring needed to protect and link the total circuit.

The blower motor is installed in the A/C evaporator core housing, which is part of the A/C evaporator case. The blower motor is connected to the electrical circuit with one hard shell connector located on the blower motor, which feeds back through the relay.

The mode function switch is installed on the A/C control and, with the heater blower motor switch resistor, provides four operating speeds.

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

The heater blower motor switch is connected in series with the A/C cycling switch to control A/C compressor operation.

The A/C cycling switch is located on top of the suction accumulator/drier assembly and controls cycling of A/C clutch. When the pressure rises to 276-324kPa (40-47 psi), the A/C cycling switch closes. When the pressure drops to approximately 152-179 kPa (22-26 psi), the A/C cycling switch opens to stop the A/C compressor operation. In ambient temperatures below approximately 10°C (50°F), the A/C cycling switch will not allow A/C compressor operation because low system pressures are not high enough to close the switch.



Relays

A/C Time Delay and WOT Cutout Relay

The air conditioning system is monitored and regulated by the closed loop engine control system. This system, working through the wide-open throttle (WOT) relay disengages the A/C clutch under the following conditions:

^ Immediately after start-up.

^ For a brief interval during wide open throttle performance to allow extra engine power for passing.

^ When engine coolant temperature approaches an overheating condition.

^ When engine idle rpm is approaching its stall speed. In addition, the closed loop engine control system senses the output of the A/C cycling switch and momentarily delays engaging the A/C clutch when engine idle rpm is boosted to an acceptable rate. Briefly, closed loop engine control provides smooth engine performance at slower speeds, as well as when the engine is operating in the idle range.