System Outline

1. HEATER BLOWER MOTOR OPERATION
Current is applied at all times through heater fuse to TERMINAL 5 of Heater Relay. When the Ignition SW is turned ON, current flows through GAUGE fuse to TERMINAL 1 of Heater Relay --> TERMINAL 3 --> TERMINAL HR of A/C Control Assembly. At the same time, current also flows from GAUGE fuse to TERMINAL IG of A/C Control Assembly and TERMINAL 5 of extra High Speed Relay --> TERMINAL 3 --> TERMINAL FR of A/C Control Assembly.

* Low Speed Operation
When the Blower SW (A/C Control Assembly) is moved 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 ON. As a result, the current to TERMINAL 5 of Heater Relay flows to TERMINAL 4 of relay --> TERMINAL 2 of Blower Motor --> TERMINAL 1 --> TERMINAL 1 of A/C Power Transistor --> TERMINAL 4 --> GROUND and causes the Blower Motor to rotate at low speed.

* High Speed Operation
When the Blower SW (A/C Control Assembly) is moved to HIGH 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 ON. At the same time, the current to TERMINAL 5 of extra high speed relay also to TERMINAL 3 of relay --> TERMINAL FR of A/C Control Assembly --> TERMINAL GND --> GROUND and turns the extra high speed relay ON. As a result, the current to TERMINAL 5 of Heater Relay flows to TERMINAL 4 --> TERMINAL 2 of Blower Motor --> TERMINAL 1 --> TERMINAL 1 of extra high speed relay --> TERMINAL 2 --> GROUND without passing through the Blower Resistor, causing the Blower Motor to rotate at high speed.

* Medium Speed Operation
When the Blower SW (A/C Control Assembly) is moved to MED 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 BLW --> TERMINAL 2 of A/C Power Transistor --> TERMINAL 1 --> TERMINAL 1 of the Blower Resistor --> TERMINAL 2 --> GROUND.

As a result, the current to TERMINAL 5 of Heater Relay flows to TERMINAL 4 --> TERMINAL 2 of Blower Motor --> TERMINAL 1 --> TERMINAL 1 of A/C Power Transistor --> TERMINAL 4 --> GROUND and Blower Motor is rotated at medium speed by the A/C Control Assembly controlling the current flow from TERMINAL 2 of A/C Power Transistor to TERMINAL 4.

* Auto Function
When the Auto SW in Heater Control SW (A/C Control Assembly) is selected, the current flow is the same for MED position, but the A/C Control Assembly decides the appropriate air flow volume according to the set temperature and the input signals from each sensor. By controlling the current flow from TERMINAL BLW of the A/C Control Assembly to TERMINAL 2 of A/C Power Transistor --> TERMINAL 4 --> GROUND, the A/C Control Assembly controls the Blower Motor steplessly.

2. OPERATION AIR INLET CONTROL SERVO MOTOR
(Switching from Fresh to RECIRC)
With Ignition SW turned ON, the current flows from GAUGE fuse to TERMINAL IG of A/C Control Assembly --> TERMINAL AIR --> TERMINAL 2 of Air Inlet Control Servo Motor --> TERMINAL 1 --> TERMINAL AIF 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 3 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 AIF --> TERMINAL 1 of Air Inlet Control Servo Motor --> TERMINAL 2 --> TERMINAL AIRof 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
When ignition SW turned ON, the current flows from GAUGE fuse to TERMINAL IG of A/C Control Assembly.

(Switching from DEF to FACE)
The current flows from TERMINAL FACE of A/C Control Assembly --> TERMINAL 4 of Air Vent Mode Control Servo Motor --> TERMINAL 8 --> TERMINAL 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 FACE position, the damper position signal is input from TERMINAL 8 of the Servo Motor to the TERMINAL DEF 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 DEF of A/C Control Assembly --> TERMINAL 8 of Air Vent Control Servo Motor --> TERMINAL 4 --> TERMINAL 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 "Cool" side the current flows from TERMINAL AMC of A/C Control Assembly --> TERMINAL 1 of Air Mix Control Servo Motor --> Motor --> TERMINAL 2 --> TERMINAL AMH of A/C Control Assembly --> GROUND and the motor rotates. The damper opening angle at this time is input from TERMINAL 3 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 AMH of A/C Control Assembly --> TERMINAL 2 of Air Mix Control Servo Motor --> Motor --> TERMINAL 1 --> TERMINAL AMC 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 ambient temp. sensor, coolant temperature from the A/C Thermistor 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 GAUGE fuse to TERMINAL 1 of A/C MGN Relay --> TERMINAL 2 --> TERMINAL MGC of A/C Control Assembly --> TERMINAL GND -->GROUND, turning the A/C MGN Relay ON, so that the Magnetic Clutch is ON and the A/C Compressor operates.

At the same time, the Engine Control Module detects the Magnetic Clutch is ON and the A/C compressor operates.

Open direction to avoid lowering the engine rpm during A/C operating.

If the A/C Control Assembly detects the following conditions, it stops the air conditioning.

* The temperature at the air vents is low.
* There is a marked difference between the compressor speed and the engine speed.
* The refrigerant pressure is abnormally high or abnormally low.
* The engine speed decreases.
* Rapid acceleration occurs.