System Outline

1. HEATER BLOWER MOTOR OPERATION
Current is applied at all times through HTR fuse (60 A) to TERMINAL 5 of heater relay. When the Ignition SW is turned ON, current flows through HTR fuse (10 A) to TERMINAL 1 of heater relay --> TERMINAL 3 --> TERMINAL 'HR' of A/C Control Assembly. At the same time, current also flows from HTR fuse (10 A) to TERMINAL 'IG' of A/C Control Assembly and TERMINAL 2 of VSV (for water valve) --> TERMINAL 1 --> TERMINAL 'W/V' of A/C Control Assembly.

- Low Speed Operation
When the blower SW (A/C Control Assembly) is pushed to LOW SPEED position, the current to TERMINAL 'HR' of A/C Control Assembly flows to TERMINAL 'GND' of A/C Control Assembly --> GROUND and turns the heater relay. As a result, the current to TERMINAL 5 of heater relay flows to TERMINAL 4 of the relay --> TERMINAL 2 of blower motor --> TERMINAL 1 --> TERMINAL 2 of blower resistor --> TERMINAL 1 --> GROUND and causes the blower motor to rotate at low speed.

- Medium (M1, M2, M3) And High Speed Operation
When the blower SW (A/C Control Assembly) is selected to MEDIUM (M1, M2, M3) or HIGH position, the current to TERMINAL 'HR' of A/C Control Assembly flows to TERMINAL GND --> GROUND and turns the heater relay ON. Then, the current to TERMINAL 'IG' of A/C Control Assembly flows to TERMINAL 'BLR' --> TERMINAL B-2 of power transistor --> TERMINAL A -->GROUND.

As a result, the current to TERMINAL 5 of heater relay flows to TERMINAL 4 --> TERMINAL 2 of blower motor --> TERMINAL 1 --> TERMINAL A-2 of power transistor -->TERMINAL A-1 --> GROUND and blower motor is rotated at selected speed by the A/C Control Assembly controlling the current flow from TERMINAL B-2 of power transistor to TERMINAL B-1

- Auto Function
When the auto SW in heater control SW (A/C Control Assembly) is selected, the current flow is the same as above mentions, but the A/C Control Assembly decides the appropriate air flow volume according to set temperature and the input signals from each sensor. By controlling the current flow from TERMINAL 'BLR' of the A/C Control Assembly to TERMINAL B-2 of power transistor --> TERMINAL A-1 --> GROUND, the A/C Control Assembly controls the blower motor steplessly.

2. OPERATION OF AIR INLET CONTROL SERVO MOTOR
(Switching from Fresh to RECIRC)
With Ignition SW turned ON, the current flows from HTR fuse (10 A) to TERMINAL 'IG' of A/C Control Assembly --> TERMINAL 'M REC' --> TERMINAL 6 of air inlet control servo motor --> TERMINAL 2 --> TERMINAL 'M FRS' of A/C Control Assembly --> TERMINAL 'GND' --> GROUND, the motor rotates and the damper moves to the RECIRC side. When the damper operates with the A/C SW at RECIRC position, the DAMPER position signal is input from TERMINAL 5 of the servo motor to TERMINAL 'TPI' of the ECU (built into the A/C Control Assembly). As a result, current to the servo motor circuit is cut OFF by the ECU, so the damper stops at that position.

(Switching from RECIRC to Fresh)
With Ignition SW turned ON, when the RECIRC/Fresh SW is switched to the fresh side, the current flows from TERMINAL 'IG' of A/C Control Assembly --> TERMINAL 'M FRS' --> TERMINAL 2 of air inlet control servo motor --> TERMINAL 6 --> TERMINAL 'M REC' of A/C Control Assembly --> TERMINAL 'GND' --> GROUND, the motor rotates and the damper stops at that position.

3. OPERATION OF AIR VENT MODE CONTROL SERVO MOTOR
With Ignition SW turned ON, the current flows from HTR fuse (10 A) to TERMINAL 'IG' of A/C Control Assembly.

(Switching from DEF to Face)
The current flows from TERMINAL 'M FACE' of A/C Control Assembly --> TERMINAL 4 of air vent control servo motor --> TERMINAL 5 --> TERMINAL 'M DEF' of A/C Control Assembly --> TERMINAL 'GND' --> GROUND. The motor rotates and the damper moves to the Face side. When the damper operates with the A/C SW at FACEposition, the damper position signal is input from TERMINAL 1 of the servo motor to the TERMINAL 'TPM' of the ECU (built into the A/C Control Assembly). As a result, current to the servo motor circuit is cut OFF by the ECU. So the damper stops at that position.

(Switching from Face to DEF)
The current flows from TERMINAL 'M DEF' of A/C Control Assembly --> TERMINAL 5 of air vent control servo motor --> TERMINAL 4 --> TERMINAL 'M FACE' of A/C Control Assembly --> TERMINAL 'GND' --> GROUND, the motor rotates and the damper stops at that position.

4. OPERATION OF AIR MIX CONTROL SERVO MOTOR
When the temperature SW is turned to the "cool" side, the current flows from TERMINAL 'MC' of A/C Control Assembly --> TERMINAL 4 of air mix control servo motor --> Motor --> TERMINAL 5 --> TERMINAL 'MH' of A/C Control Assembly --> GROUND and the motor rotates. The damper opening angle at this time is input from TERMINAL 1 of servo motor to --> TERMINAL 'TP' of A/C Control Assembly, this is used to determine the DAMPER STOP position and maintain the set temperature.

When the temperature control SW is turned to the "hot" side, the current flows from servo motor --> TERMINAL 'MN' of A/C Control Assembly --> TERMINAL 5 of air mix control servo motor --> Motor --> TERMINAL 1 --> TERMINAL 'MC' of A/C Control Assembly, rotating the motor in reverse and switching the damper from cool to hot side.

5. AIR CONDITIONING OPERATION
The A/C Control Assembly receives various signals, i.e.. the engine rpm from the Igniter, outlet temperature signal from the A/C Thermistor, coolant temperature from the engine coolant temp. sensor (water temp. sensor) and the lock signal from the A/C compressor, etc.

When the engine is started and the A/C SW (A/C Control Assembly) is ON, a signal is input to the ECU (built in the A/C Control Assembly). As a result, the Ground circuit in A/C Control Assembly is closed and current flows from HTR fuse (10 A) to TERMINAL 1 of A/C ECU --> TERMINAL 2 --> TERMINAL 'ACMG' of Engine Control Module (engine and Electronic Controlled Transmission ECU) --> TERMINAL 'GND' of A/C Control Assembly --> GROUND, turning the relay ON, so that the A/C magnetic clutch is ON and the A/C compressor operates.

At the same time, the Engine Control Module (engine and Electronic Controlled Transmission ECU) detects the magnetic clutch is ON and the A/C compressor operates. Open direction to avoid lowering the engine rpm during A/C operating. When any of the following signals are input to the A/C Control Assembly, the control assembly operates to turn OFF the air conditioning.

- Engine high temp. signal is high.
- Coolant high temp. signal is high.
- A signal that the temperature at the air outlet is low.
- A signal that there is a large difference between engine speed and compressor speed.
^ A signal that the refrigerant pressure is abnormally high or low.