System Outline

1. HEATER BLOWER OPERATION
Manual Blower Operation
When the Blower Control SW is set to any Blower speeds, the A/C Amplifier operates and the current to drive the Blower Motor flows from TERMINAL BLW of the A/C Amplifier to TERMINAL SI of the Blower Motor Control Relay. The current activates the Relay and the voltage applied to TERMINAL +B of the Blower Motor Control Relay is output at TERMINAL M+ as the voltage for the selected Blower speed. The current then flows from TERMINAL M+ of the Blower Motor Control Relay to TERMINAL 2 --> TERMINAL 1 --> TERMINAL M- of Blower Motor Control Relay --> TERMINAL GND --> GROUND, and the Blower Motor operates at the Blower speed selected.

Auto Function
When the Auto SW is turned ON, the A/C Amplifier calculates the required vent temperature based on the set temperature and input from each sensor. Then TERMINAL BLW of the A/C amplifier inputs current to TERMINAL SI of the Blower Motor Control Relay in conformity with the required vent output. This current activates the Blower Motor Control Relay so that current flows from TERMINAL M+ of the Blower Motor Control Relay --> TERMINAL 2 of Blower Motor --> TERMINAL 1 --> TERMINAL M- of Blower Motor Control Relay --> TERMINAL GND --> GROUND, activating the Blower Motor. The Blower Motor then operates at different steps in conformity with variable current flow output from TERMINAL BLW of the A/C Amplifier to TERMINAL SI of the Blower Motor Control Relay.

2. OPERATION OF AIR INLET CONTROL SERVO MOTOR
(Switching From Fresh To Recirc)
With Ignition SW turned ON, the current flows from HTR fuse to TERMINAL 2 of Air Inlet Control Servo Motor -->TERMINAL 5 --> TERMINAL AIR of A/C Amplifier --> TERMINAL GND --> GROUND,the Motor rotates and the damper stops at RECIRC position.
(Switching From Recirc To Fresh)
With Ignition SW turned ON, the current flows from HTR fuse to TERMINAL 2 of Air Inlet Control Servo Motor --> TERMINAL 3 --> TERMINAL AIF of A/C Amplifier --> TERMINAL GND --> GROUND, the Motor rotates and the damper stops at FRESH position.

3. OPERATION OF AIR VENT MODE CONTROL SERVO MOTOR
With Ignition SW turned ON, the current flows from HTR fuse to TERMINAL IG of A/C Amplifier
(Switching From Def To Face)
The current from TERMINAL AOF of A/C Amplifier --> TERMINAL 1 of Air vent mode Control Servo Motor --> TERMINAL 2 --> TERMINAL AOD of A/C Amplifier --> TERMINAL GND --> GROUND. The Motor rotates and the damper moves to face side. When the damper operates with the A/C SW at FACE position, the damper position signal is input from TERMINAL 3 of the Servo Motor to the TERMINAL TPO of the A/C Amplifier. As a result, current to the Servo Motor Circuit is Cut OFF by the Amplifier, so the damper stops at that position.
(Switching From Face To Def)
The current flows from TERMINAL AOD of A/C Amplifier --> TERMINAL 2 of Air vent Mode Control Servo Motor --> TERMINAL 1 --> TERMINAL AOF of A/C Amplifier --> 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 AMC of A/C Amplifier --> TERMINAL 1 of air mix Control Servo Motor --> Motor --> TERMINAL 2 --> TERMINAL AMH of A/C Amplifier --> TERMINAL GND --> 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 "Warm" side, the current flows from TERMINAL AMH of A/C Amplifier --> TERMINAL 2of Air mix Control Servo Motor --> Motor --> TERMINAL 1 --> TERMINAL AMC of A/C Amplifier, rotating the Motor in reverse and switching the damper from cool to warm side.

5. AIR CONDITIONING OPERATION
The A/C Amplifier 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 (EFI Water Temp. Sensor) and the Lock Signal from the A/C Compressor, etc.

When the Engine is started and the A/C SW (Heater Control SW) is ON, a Signal is Input to the A/C Amplifier. As a result, the Ground Circuit in A/C Amplifier is closed and current flows from HTR fuse to TERMINAL 1 of A/C Magnetic clutch Relay --> TERMINAL 2 --> TERMINAL ACMG of Engine Control Module --> TERMINAL A/C --> TERMINAL MGC of A/C Amplifier --> TERMINAL GND --> GROUND, turning the Relay ON, so that the A/C Magnetic clutch is ON and the A/C Amplifier operates.

At the same time, the Engine Control Module detects the Magnetic clutch is ON and the A/C Amplifier is operating and opens direction to avoid lowering the Engine RPM during A/C operating.

When any of the following signals are input to the A/C Amplifier operates to turn OFF the Air conditioning.

^ Engine RPM 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