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.