System Outline

1. FRONT HEATER BLOWER MOTOR OPERATION
With the ignition SW ON, current flowing through the A/C fuse flows to TERMINAL 5 of the front heater blower relay --> TERMINAL 3 --> TERMINAL 5 of the heater blower SW.
(Low Speed Operation)
When the heater blower SW is set at LO position, current flowing to TERMINAL 5 of the blower SW flows to TERMINAL 6 --> GROUND, turning the heater relay ON. Current flow through 40A front heater CB flows to TERMINAL 1 of the heater relay --> TERMINAL 2 --> TERMINAL 2 of the blower motor --> TERMINAL 1 --> TERMINAL 1 of the blower resistor --> TERMINAL 4 --> GROUND, causing the blower motor to rotate at low speed. (Operation at speed M1 (I) M2 (II))
When the blower SW is set at M1 position, current flowing to TERMINAL 5 of the blower SW flows to TERMINAL 6 --> GROUND. Turning the heater relay ON, current flow through 40A front heater CB flows to heater relay --> BLOWER MOTOR --> TERMINAL 1 of the blower resistor --> TERMINAL 2 --> TERMINAL 1 of the blower SW --> TERMINAL 6 --> GROUND, the resistance of the blower resistor is less than at low speed so the blower motor turns faster. When the SW is set at M2 position, current flowing through the motor flows from TERMINAL 1 of the blower resistor --> TERMINAL 3 --> TERMINAL 2 of the blower SW --> TERMINAL 6 --> GROUND, resistance of the blower resistor is less than at M1 speed, so the blower motor turns even faster than at M1 speed.
(High Speed Operation)
When the blower SW is set at HI position, the heater relay and front heater (HI) relay turns ON the current flowing through the blower motor flows to TERMINAL 2 of the front heater (HI) relay --> TERMINAL 1 --> GROUND, and bypassing blower resistor, the blower motor turns at high speed.

2. REAR BLOWER MOTOR OPERATION
^ Nippondenso Type
When the ignition SW is turned ON, current flowing through the A/C fuse flows from TERMINAL 5 of the rear A/C relay --> TERMINAL 3 --> TERMINAL 4 of the rear A/C SW.
(Low Speed Operation)
When the rear A/C SW is set at LO position, current flowing to TERMINAL 5 of the rear A/C relay flows to TERMINAL 3 --> TERMINAL 4 of the rear A/C SW --> TERMINAL 3 --> GROUND, turning the rear A/C relay ON. Then current flows from the A/C fuse (for rear) to TERMINAL 1 of the rear A/C relay --> TERMINAL 2 --> BLOWER MOTOR fuse --> TERMINAL 2 of the blower motor --> TERMINAL 1 --> TERMINAL 1 of the blower resistor --> TERMINAL 3 --> GROUND, causing the blower motor to turn at low speed.
(Medium Speed Operation)
With the rear A/C SW is set at N position, current flowing through the blower motor flows to TERMINAL 1 of the blower resistor --> TERMINAL 2 --> TERMINAL 1 of the rear A/C SW --> TERMINAL 3 --> GROUND, the resistance of the blower resistor is less than that at low speed so the blower motor turns faster.
(High Speed Operation)
With the rear A/C SW is set at HI position, current flowing through the blower motor flows, without passing through the blower resistor, to TERMINAL 2 of the rear A/C SW --> TERMINAL 3 --> GROUND, so that the blower motor turns at the highest speed.
^ Panasonic Type
When the ignition SW is turned ON, current flowing through the A/C fuse flows from TERMINAL 5 of the rear A/C relay --> TERMINAL 3 --> TERMINAL 4 of the rear A/C SW.
(Low Speed Operation)
When the rear A/C SW is set at LO position, current flowing to TERMINAL 5 of the rear A/C relay flows to TERMINAL 3 --> TERMINAL 4 of the rear A/C SW --> TERMINAL 3 --> GROUND, turning the rear A/C relay ON. Then current flows from the A/C fuse (for rear) to TERMINAL 1 of the rear A/C relay --> TERMINAL 2 --> BLOWER MOTOR fuse --> TERMINAL 1 of the blower motor --> TERMINAL 2 --> TERMINAL 3 of the blower resistor --> TERMINAL 2 --> GROUND, causing the blower motor to turn at low speed.
(Medium Speed Operation)
With the rear A/C SW is set at N position, current flowing through the blower motor flows to TERMINAL 3 of the blower resistor --> TERMINAL 1 --> TERMINAL 1 of the rear A/C SW --> TERMINAL 3 --> GROUND, the resistance of the blower resistor is less than that at low speed so the blower motor turns faster.
(High Speed Operation)
With the rear A/C SW is set at HI position, current flowing through the blower motor flows, without passing through the blower resistor, to TERMINAL 2 of the rear A/C SW --> TERMINAL 3 --> GROUND, so that the blower motor turns at the high speed.

3. AIR CONDITIONING OPERATION
With the ignition SW ON, current flowing through the A/C fuse flows through each component to TERMINAL 4 of the A/C SW, and to TERMINAL 10 of the A/C amplifier.
(Operation Of Front A/C)
Input into the A/C amplifier are engine speed signals from the igniter and the evaporator temp. signals from the A/C thermistor. When the engine is running, the A/C SW is ON and the blower SW is at the desired speed, a signal is also input to TERMINAL 10 of the A/C amplifier. This causes the amplifier to operate and the magnetic clutch relay, magnetic valve (front) and A/C IDLE-UP VSV all to turn ON. At the same time, the current flowing through the A/C fuse flows to TERMINAL 2 of the magnetic clutch relay --> TERMINAL 4 --> TERMINAL 1 of magnetic clutch --> TERMINAL 2 --> GROUND, causing the compressor to operate.
If the engine speed falls to approx. 600 rpm or below, a signal is input that the evaporator temp. is low, or a signal is input that the refrigerant pressure is either abnormally high or low and the amplifier functions to turn A/C off.
(Operation of rear A/C) Input into the A/C amplifier are engine speed signals and evaporator temp. signals from the A/C thermistor. When the engine is running, a signal that rear A/C SW is ON is input to TERMINAL 12, the amplifier operates and the magnetic clutch relay, magnetic valve (rear) and A/C IDLE-UP VSV turn ON. At the same time, the current flowing through the A/C fuse flows in the same way as for the front A/C, causing the compressor to operate.