Mazda Training manual — part 281

AIR CONDITIONING
SG01 - Basic System

SG01-3

TC070-15-01H

A/C unit construction/operation

• The figure below shows A/C unit which integrates the blower, cooling and heater

units.

1. Evaporator*
2. Heater core*
3. Expansion valve
4. Air intake door*
5. Air mix door*
6. Airflow mode door*
7. Evaporator temperature
sensor*
8. Resistor (manual air conditioner)
9. Power MOS FET (full-auto air conditioner)
10. Air intake actuator
11. Air mix actuator (full-auto air conditioner)
12. Airflow mode actuator (full-auto air conditioner)
13. Blower motor*
14. Airflow mode main link

* Also refer to the figure below “Ventilation System”

Ventilation System

AIR CONDITIONING
SG01 - Basic System

SG01-4

TC070-15-01H

Evaporator
• The figure below shows a double-tank drawn cup.

1. Separation part
2. Rejoining point
3. Separation part
4. Rejoining point










Expansion valve

• The liquid refrigerant of about 1.5 MPa is sprayed at the expansion valve. The

splayed refrigerant is, then, expanded its volume that causes its pressure decreased
to about 0.2 MPa. This makes the refrigerant to be vaporized causing reduction of
temperature. The expansion valve regulates the flow volume of the refrigerant.

• 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.

AIR CONDITIONING
SG01 - Basic System

SG01-5

TC070-15-01H

Air Mix Door Operation

• 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.

Airflow Mode Door Operation
• 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.

AIR CONDITIONING
SG01 - Basic System

SG01-6

TC070-15-01H

Air filter function

• The figure below shows air filter that can remove pollen and dust has been added.
• The air filter cannot be reused and must be replaced periodically.

NOTE

Even new air filters are gray; be careful not to mistake the gray color as dirt.

A/C compressor

• A rotary-vane type (H12A1) A/C compressor body has been adopted for size,
weight, and operation vibration reduction.

1. Magnetic clutch
2. Thermal protector
3. A/C compressor