Heating and Air Conditioning: Description and Operation

AIR CONDITIONING: AIR CONDITIONING SYSTEM: SYSTEM DIAGRAM














SYSTEM DESCRIPTION

1. GENERAL

The air conditioning system has the following controls:





2. MODE POSITION AND DAMPER OPERATION

(a) Mode Position and Damper Operation





Functions of Main Dampers:





3. AIR OUTLETS AND AIRFLOW VOLUME

(a) Air Outlets and Airflow Volume









The size of the circle o indicates the proportion of airflow volume.

4. A/C COMPRESSOR

(a) General

(1) An A/C compressor is a continuously variable capacity type in which its capacity varies in accordance with the cooling load of the air conditioner.

(2) This compressor consists of the shaft, lug plate, piston, shoe, crank chamber, cylinder, and solenoid control valve.

(3) The solenoid control valve that adjusts the suction pressure so that the suction pressure can be controlled as desired is provided.

(4) The plastic DL (Damper Limiter) type A/C pulley is used.





(b) Operation

(1) The crank chamber is connected to the suction passage. A solenoid control valve is provided between the suction passage (low pressure) and the discharge passage (high pressure).

(2) The solenoid control valve operates under duty cycle control in accordance with the signals from the air conditioning amplifier.





(3) When the solenoid control valve closes (solenoid coil is energized), a difference in pressure is created and the pressure in the crank chamber decreases. Then, the pressure that is applied to the right side of the piston becomes greater than the pressure that is applied to the left side of the piston. This compresses the spring and tilts the lug plate. As a result, the piston stroke increases and the discharge capacity increases.





(4) When the solenoid control valve opens (solenoid coil is not energized), the difference in pressure disappears. Then, the pressure that is applied to the left side of the piston becomes the same as the pressure that is applied to the right side of the piston. Thus, the spring elongates and eliminates the tilt of the lag plate. As a result, there is small piston stroke and the discharge capacity decreases.





5. AMBIENT TEMPERATURE SENSOR

The ambient temperature sensor detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the A/C amplifier.

6. EVAPORATOR TEMPERATURE SENSOR

The evaporator temperature sensor detects the temperature of the cool air immediately past the evaporator in the form of resistance changes, and outputs it to the A/C amplifier.

7. A/C PRESSURE SENSOR

The A/C pressure sensor detects the refrigerant pressure and outputs it to the A/C amplifier in the form of voltage changes.