Mazda Training manual - part 264

Air Conditioning Fundamentals

TC070-05-01S

5 – AIR CONDITIONING   
COMPONENTS 

 

30

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Most vane-type compressors use a temperature-protection switch 
mounted on the compressor. This switch shuts down the compressor if it 
gets too hot. 

 

The variable displacement vane-type compressor changes its pumping 
capacity to compensate for load. A single control valve controls 
compressor displacement like the variable displacement piston 
compressor. A rotating plate throttles the volume of refrigerant entering 
the compression chamber. 

 

 

Vane-type pumps have several advantages over piston-type pumps. They 
are: 

 

• Smaller 

 

• Lighter 

 

• More efficient 

 

 • Have very few moving parts 

 

FIGURE 14. The 
vane-type 
compressor 
provides low- 
friction operation 
by having vanes 
and a rotor in an 
elliptical housing. 

 

Front shaft

 

Seal

 

Rear shaft

 

Bearing

 

Rear housing

 

Vane

 

Front housing

 

Bearing

 

 

Air Conditioning Fundamentals

TC070-05-01S

5 – AIR CONDITIONING   
COMPONENTS 

 

31

 

 

 
 
 
 

FIGURE 15. The 
condenser 
transfers heat 
from the 
compressed 
refrigerant vapor 
to the outside air. 
As the 
refrigerant cools, 
it changes into a 
liquid, releasing 
latent heat of 
condensation.

 

 

CONDENSER 
 
The condenser (Figure 15) is located in front of the radiator. It receives hot, 
high- pressure refrigerant gas from the compressor and transfers the heat 
to the outside air. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Like the evaporator, the condenser circulates refrigerant through a series 
of tubes and fins. A fan draws outside air over the condenser’s surface 
area, allowing the hot refrigerant to pass its heat to the air (latent heat of 
condensation). 

 

As the refrigerant cools, it changes from a high-pressure gas to a 
high-pressure liquid. After changing from a vapor to a liquid, the refrigerant 
undergoes additional cooling in the bottom of the condenser (sub-cooling). 

 

The efficiency of the condenser is critical to A/C operation. The outside air 
must absorb the stored heat from the vehicle interior plus the additional 
heat that results from compressing the gas. The more heat transferred by 
the condenser, the more cooling the evaporator can provide. For example, 
a larger capacity condenser and a more efficient fan will drop the interior 
cooling temperature significantly. 

 

To prevent damage to A/C components, any malfunction in the condenser 
fan normally causes the A/C system to shut down by opening the circuit to 
the compressor clutch. 

 
 
 
 
 
 
 
 

In

Out

Air Conditioning Fundamentals

TC070-05-01S

5 – AIR CONDITIONING   
COMPONENTS 

 

32

REVIEW EXERCISE 4 
 
Fill in the words that correctly complete these sentences. Check your answers with the 
answer key on page 34. 
 
1. 

The compressor receives warm, low-pressure refrigerant vapor from the 

_________________________. 

 
2.      The two main types of compressors commonly used today are the 

_________________________ type and the _________________________ type. 

 
3.  The back-and-forth movement of the ___________    __________ moves the 

compressor’s pistons back and forth in their cylinders. 

 
4.    Which type of A/C compressor is lighter and smaller? _________________________ 
 
5.    The condenser receives hot, high-pressure refrigerant vapor from the 

_________________________. 

 
6.  _________________________-ended piston compressors have all of their piston 

cylinders mounted side-by-side in the compressor. 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Air Conditioning Fundamentals

TC070-05-01S

5 – AIR CONDITIONING   
COMPONENTS 

 

33

 

 
 
 
 
 
 
 

 
FIGURE 16. The 
receiver / dryer 
collects 
moisture and 
contaminants 
from the 
refrigerant and 
stores 
refrigerant to 
keep system 
pressures 
constant. 
 

Receiver tube 

Dessicant

 

 
 
 
 
 

Answers to 
Review 
Exercise 4 
 
1.  evaporator 
2.  axial (piston); 

vane (non- 
piston) 

3.  swash plate 
4.  vane type 
5. compressor 
6.  single

 

 
 
 

RECEIVER / DRYER 
 
Located near the outlet of the condenser, the receiver / dryer (Figure 16) 
filters moisture and foreign matter from the liquid refrigerant and serves as 
a storage area for refrigerant. This storage area traps any refrigerant not 
completely liquefied in the condenser. Any remaining gaseous refrigerant 
could damage the expansion valve or evaporator. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The moisture-collecting material in the receiver / dryer (called desiccant) 
matches the type of refrigerant used in the system, either R-12 or R-134a. 
If the receiver / dryer collects excessive moisture from the refrigerant, it 
can freeze and block the liquid refrigerant from reaching the evaporator. If 
this happens, the A/C system will usually produce normal cooling at first, 
followed by slowly diminished cooling.