Mazda Training manual - part 277

Air Conditioning Fundamentals

TC070-05-01S

   

COURSE SUMMARY 

 

82

The following pages, contain a brief summary of the important points covered in this Guide. 
Before taking the final examination, review this summary to verify your understanding of the 
material. 
 
 
 
SAFETY PRECAUTIONS 
 
Refrigerant can cause severe drying and frostbite if it comes in contact with exposed skin. It 
is extremely important to follow safety precautions when working with A/C systems. To help 
prevent injury, always wear goggles and gloves. 
 
 
 
PHYSICAL LAWS 
 
 
Air conditioning systems are based on the following fundamental physical laws: 
 
• Heat 

flow 

 
• Heat 

absorption 

 
• Pressure 
 
• Boiling 

points 

 
Air conditioning systems cool the vehicle interior by absorbing heat into the evaporator. 
Heat travels to cold until the temperatures equalize. 
 
 
 
A/C SYSTEM COMPONENTS 
 
 
The basic components of the A/C system are: 
 
• Compressor 
 
• Condenser 
 
• 

Receiver/dryer or accumulator 

 
• 

Expansion valve or orifice tube 

 
• Evaporator 
 

Air Conditioning Fundamentals

TC070-05-01S

   

COURSE SUMMARY 

 

83

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Answers to Review 
Exercise 12 

 

1.  high

 

2. liquid 
3. liquid 
4. gaseous 
 

Compressor 
 
 
 
The compressor draws in low-pressure vapor from the evaporator and 
compresses it into hot, high-pressure vapor and then sends it to the 
condenser. The compressor also pumps the refrigerant throughout the 
A/C system. 
 
 
Condenser 
 
The condenser is located in front of the radiator. It removes heat from 
the refrigerant, causing it to condense it into a high-pressure liquid. 
 
 
Receiver / Dryer 
 
The receiver / dryer, located at the outlet to the condenser, is a storage 
tank for liquid refrigerant. It also contains a desiccant that removes 
moisture and a filter to trap contamination. A receiver/dryer is used in 
AC systems that have an expansion valve. 
 
 
Accumulator 
 
The accumulator is used with a fixed orifice system. The accumulator is 
located at the outlet of the evaporator and prevents liquid refrigerant 
from reaching the compressor. It also filters out particles and removes 
moisture from the refrigerant. 
 
 
Expansion Valve / Orifice Tube 
 
The expansion valve or orifice tube regulates refrigerant flow into the 
evaporator to allow maximum cooling and ensure complete evaporation 
of the refrigerant. 
 
 
Evaporator 
 
The evaporator, located under the vehicle dash, evaporates the 
refrigerant that allows it to absorb interior heat. During evaporation, 
any moisture (humidity) in the air condenses on the outside of the 
evaporator and is drained away. 

 

Air Conditioning Fundamentals

TC070-05-01S

   

COURSE SUMMARY 

 

84

REFRIGERANTS 
 
R-12 and R-134A are refrigerants used in automotive A/C systems. They are not 
interchangeable. R-12 uses mineral-based lubricating oil, while R-134A uses synthetic PAG 
oil. The oils are not interchangeable and must never be mixed in the same system. 
 
 
Most systems produced today use R-134A refrigerant. Federal law requires that 
R-12 refrigerant production be stopped by the year 2000. 
 
 
 
A/C SERVICING 
 
Moisture in an A/C system is very destructive. It can freeze in the expansion valve, 
preventing refrigerant flow and cooling. Water, when combined with R-12, forms 
hydrochloric acid, which is very corrosive and can damage A/C components and create 
leaks. 
 
Proper refrigerant recovery and charging equipment must be used to prevent refrigerant 
from entering the atmosphere, where it can damage the ozone layer. Refrigerant equipment 
includes a manifold gauge set, service valves, vacuum pump, charging station, charging 
cylinder, recovery / recycling system, and leak detection devices. 
 
Whenever the A/C system is open, it must be properly evacuated to remove moisture and 
prevent the formation of hydrochloric acid in R-12 systems. 
 

 

 

 

© Copyright, 2005 Mazda Motor Corporation. All Rights Reserved 

All materials (texts, images, graphics, and other materials) on the 
documents are subject to the copyrights and other intellectual 
property rights of Mazda Motor Corporation, its affiliated 
companies, and its licensors. These materials may not be copied, 
processed, sold, inspected, published not only for commercial 
use but also for third party, and these materials may not be 
modified or reproduced in any medium without the written 
authorization of Mazda Motor Corporation.