System Outline

1. HEATER BLOWER OPERATION
Manual operation When the blower speed is set ant any speed by the blower control SW, the center ECU sends a signal to the blower motor controller, and controls the blower motor speed. Auto operation When the auto SW is operated, the center ECU sends signals to the blower motor controller, according to the signals from respective sensors, commands from the temperature SW etc., and controls the blower motor automatically.

2. AIR INLET CONTROL SERVO MOTOR CONTROL
When the FRESH/RECIRC select SW is switched to RECIRC, the motor in the air inlet control servo motor rotates to move the damper to the RECIRC side. The damper position is recognized by the NC amplifier [Center ECU] TERMINAL TPI, and rotates the motor until the damper reaches its position.

When the FRESH/RECIRC select SW is switched to FRESH, the motor in the air inlet control servo motor rotates to move the damper to the FRESH side. The damper position is recognized by the NC amplifier [Center ECU] TERMINAL TPI, and rotates the motor until the damper reaches its position.

3. AIR VENT MODE CONTROL SERVO MOTOR
When the mode select SW in the center ECU is pushed, a signal is sent from the center ECU, and activates the air vent mode control servo motor. This causes the servo motor to rotate to the position selected using the mode select SW (FACE, BI-LEVEL, FOOT, FOOT/DEF, DEF), and moves the damper.

4. AIR MIX CONTROL SERVO MOTOR
When the temperature control SW in the center ECU is pushed, a signal is sent from the center ECU, and activates the air mix control servo motor. The motor and damper is moved until it reaches the temperature set by the temperature control SW.

5. AIR CONDITIONING OPERATION
The center ECU receives video~s signals, i. e., the engine RPM from the crankshaft position sensor, outlet temperature from the A/C ambient temp. sensor, coolant temperature from the engine coolant temp. sensor, and the lock signal from the A/C compressor, etc. When the engine is started and the NC SW is turned ON, a signal is sent to the center ECU. As a result, the A/C magnetic clutch is turned ON and operates the compressor.

In addition, when the engine control module detects that the NC magnetic clutch is ON and the NC compressor is operating, it controls the engine in the direction to avoid lowering the engine RPM during NC operation.

When any of the following signals are sent to the center ECU, the NC is turned off.
* Coolant temp. is high.
* Outlet air temp. is low.
* Large difference between the engine speed and compressor speed.
* The refrigerant pressure is abnormally high or low.

6. CONDENSER FAN MOTOR OPERATION (W/ REAR AIR CONDITIONING)
When the NC is operating and the NC single pressure SW is ON, the current flows from the A.C fuse to MG CLT relay TERMINAL 5 to TERMINAL 3 to NC condenser fan relay TERMINAL 3 to TERMINAL 4 to NC single pressure SW TERMINAL 2 to TERMINAL 3 to GROUND, and turns ON the NC condenser fan relay. As a result, the current flows from the CDS FAN fuse to NC condenser fan relay TERMINAL 1 to TERMINAL 2 to A/C condenser fan motor TERMINAL 2 to TERMINAL 1 to GROUND, and operates the NC condenser fan motor.