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