HOW YOUR A/C WORKS

The system conditions the air by cooling it and removing moisture to make you more comfortable while you drive. There are three types of air conditioning systems: orifice tube, expansion valve or a combination of the two which is found in rear air conditioning systems. The air conditioning system is made up of the following components: compressor, condenser, evaporator, orifice tube (or expansion valve), and an accumulator (or receiver-drier). Each of these components serves a different purpose. Learn more about the repetitive cycle of the system below.

ORIFICE TUBE & ACCUMULATOR SYSTEM

EXPANSION VALVE & RECEIVER-DRIER SYSTEM

UNDERSTANDING YOUR A/C SYSTEM

This short video featuring ASE-Certified Master Technician Bruce Bonebrake will help you to understand the components and basic operation of your A/C System.

WHY SHOULD I DO THE COMPLETE A/C JOB?

When you buy and install the components that make up the complete job, including a "new" compressor, your warranty period increases from a 2 year warranty to a limited lifetime warranty.

DETAILED A/C MAINTENANCE, TROUBLESHOOTING, AND REPAIR

This Haynes Techbook includes step by step procedures, easy to follow photographs, and handy tips and shortcuts BUY IT NOW

View content for UNDERSTANDING YOUR A/C SYSTEM.

A/C SYSTEM COMPONENTS

Refrigerant

The refrigerant gas used in most vehicles is commonly known as Freon or R134A. Prior to 1994 R12 was used in air conditioning systems, but was discontinued due to the highly polluting nature of the gas. The ability of the refrigerant to change its physical properties as it is compressed, cooled and metered is what makes the A/C System work.

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Compressor

The compressor is responsible for compressing the refrigerant gas, commonly known as Freon. When the gas is compressed it becomes very hot and is then sent through a condenser.

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Condenser

The condenser is a series of coils that outside air passes over to remove the heat from the compressed gas. This will cause the gas to cool and condense into a cold liquid.

  • A parallel style (non-serpentine) condenser cannot be flushed and must be replaced if it fails.
  • A serpentine-style condenser can be identified by inspecting the ends of the component and observing a snake like appearance that indicates a long singular tube that switches back several times almost like a ribbon. This style condenser can be flushed using the A/C Flush Kit available in the AutoZone Loan-A-Tool program.

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Receiver-Drier*

The receiver-drier is a canister that contains desiccant inside to absorb moisture. The receiver-drier sometimes has a sight-glass on top to observe flow (however, on retrofitted systems the sight glass will be rendered useless since the oil used with R134A is not transparent), while an accumulator will not.

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A/C Inline Filter Kit

The A/C Inline Filter Kit traps debris that even flushing cannot remove from your A/C lines.

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Expansion Valve*

The expansion valve provides a restriction in the flow of refrigerant. This restriction causes the refrigerant to change from a high-pressure liquid refrigerant into low-pressure liquid refrigerant mist before it enters the evaporator. The failure of an expansion device is usually restricted flow due to clogging.

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Orifice Tube*

The orifice tube has a conical shaped fixed orifice that provides restriction in the flow of refrigerant. This restriction causes the refrigerant to change from high pressure liquid refrigerant into low pressure liquid refrigerant mist before it enters the evaporator. The failure of an orifice tube is usually restricted flow due to clogging.

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Evaporator

As the low-pressure liquid refrigerant mist flows through the evaporator, a blower motor pushes air across the cold tubes of the evaporator to deliver cooled air into the passenger compartment of the automobile.

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Accumulator

The accumulator is a holding tank for the refrigerant exiting the evaporator. While the refrigerant is circulating inside, the accumulator desiccant bag removes any moisture that may be present.

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*Air conditioning systems will use either an orifice tube/accumulator or an expansion valve/receiver-drier set up. Some vehicles that have a rear A/C system can use a combination of the two with an additional evaporator.

 
 
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