A/C UNIT CONSTRUCTION/OPERATION

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Construction

―  Evaporator

―  Heater core

―  Expansion valve

―  Air mix door

―  Airflow mode door

―  Evaporator temperature sensor

―  Resistor (manual air conditioner)

―  Power MOS FET (full-auto air conditioner)

―  Air mix actuator (full-auto air conditioner)

―  Airflow mode actuator (full-auto air conditioner)

―  Air filter

―  Blower motor

―  PTC heater (L.H.D. MZ-CD 1.4 DI Turbo, MZ-CD 1.6 (Y6))

L.H.D.

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R.H.D.

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Evaporator

•  A tube-fin type evaporator has been adopted. By adopting a new flow pattern for the refrigerant, the cooling performance is maintained while employing a thin, lightweight evaporator.

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Expansion valve

•  The expansion valve causes a sudden decrease in the pressure of the liquid refrigerant. This atomizes the refrigerant, making it easier for the evaporator to vaporize it. The expansion valve also regulates the flow volume of the refrigerant sent to the evaporator.

•  The amount of refrigerant delivered to the evaporator is adjusted by the opening angle of the ball valve in the expansion valve.

•  Opening angle is adjusted by a balance of the R-134a pressure (Pd) in the diaphragm, and a composite force of evaporator discharge pressure (PI) against the lower part of the diaphragm and spring force (Fs) pushing up the ball valve. When PI increases, the temperature of the temperature sensor near the diaphragm rises and the Pd heated by the R-134a in the diaphragm increases. When the Pd increases more than PI + Fs, the diaphragm is pushed down, and the shaft attached to end of the temperature sensor rod pushes down the ball valve, increasing the amount of liquid refrigerant flow. When the evaporator discharge refrigerant temperature decreases, PI + Fs increases more than Pd, the ball valve is pushed up, and the amount of liquid refrigerant flow decreases.

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Operation

Air mix door

•  The air mix door, installed in the A/C unit, controls HOT or COLD position, depending on the position of the temperature control dial. As a result, airflow distribution changes, and the airflow temperature is controlled.

L.H.D.

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R.H.D.

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Airflow mode door

•  The airflow mode doors move to VENT, BI-LEVEL, HEAT, HEAT/DEF, or DEFROSTER position, depending on the position of the airflow mode selector dial. As a result, airflow mode changes.

L.H.D.

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R.H.D.

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L.H.D.

R.H.D.