Heating and Air Conditioning: Description and Operation

Condenser Fan And Front Air Conditioning

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 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 center ECU TERMINAL TPI, and rotates the motor until the damper reaches its position.
When the FRESH/RECIRC select SW is set to auto, the exhaust gas sensor in the engine room detects the ingredient of the exhaust emission, and switches the FRESH/RECIRC mode automatically.

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 various signals, i. e., the engine RPM from the crankshaft position sensor, outlet temperature from the A/C ambient temperature sensor, coolant temperature from the engine coolant temperature sensor, and the lock signal from the A/C compressor, etc. When the engine is started and the A/C SW is turned on, a signal is sent to the center ECU. As a result, the magnetic clutch is turned on and operates the compressor.
In addition, when the engine control module detects that the magnetic clutch is on and the A/C compressor is operating, it controls the engine in the direction to avoid lowering the engine RPM during A/C operation.
When any of the following signals are sent to the center ECU, the A/C is turned off.
- Coolant temperature is high.
- Outlet air temperature is low.
- Large difference between the engine speed and compressor speed.
- The refrigerant pressure is abnormally high or low.

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

Rear Air Conditioning

SYSTEM OUTLINE

1. COOLER AND HEATER BLOWER OPERATION
- Manual operation
When the blower control SW in the rear A/C control SW is set to any blower speed, a signal is sent to the A/C amplifier. The A/C amplifier controls the power transistor and operates the rear cooler blower motor and rear heater blower motor at the set speed.
- Auto operation
When the auto SW in the rear A/C control SW is operated, a signal is sent to the A/C amplifier. The A/C amplifier controls the power transistor according to the signals from respective sensors, and operates the rear cooler blower motor and rear heater blower motor.

2. AIR MIX CONTROL SERVO MOTOR CONTROL
When the temperature control lever in the rear A/C control SW is operated, a signal is sent to the A/C amplifier. The A/C amplifier controls the rear air mix control servo motor to operate the damper until it reaches the temperature set by the temperature control lever.

3 . AIR CONDITIONING OPERATION
The cooler and heater operation can be switched by the mode select SW in the rear A/C control SW.