7 Basic Parts of Car AC System (With Pics) & Their Functions

Car AC Parts

According to a SEAT expert, an interior temperature of 35°C causes the driver to react 20% slower than at 25°C.

For this reason, it is very important to keep the passenger cabin cool. A car air conditioner means a lot on hot days. If you are upset with your air conditioner. OR, If you want to know why the car air conditioner does not work or has a certain problem. OR, If you want to have more information about the car air conditioner.

So, this article is for you, both for AC technicians and for non-techie guys. In this powerful guide, you will know everything about the seven basic car AC system parts, car AC leak, and car AC leak detection methods, written in a simple way that can be understood and applied.

Car AC System

An automotive air conditioning is a system that cools the inside air of the vehicle cabin.

The main purpose of the air conditioning system is to make the internal temperature of the air lowered and comfortable for occupants. In cars, the air conditioning system cleans, dehumidifies, and circulates the interior air of the car cabin.

Parts of the Car AC System

The air conditioning system consists of different car AC system parts located under the hood and inside the cabin. All car AC system parts work together to bring comfort to the car occupant.

In the AC system, all components are interlinked together with each other to cool the inside air of the vehicle. Some of the major car components are mentioned below.

The 7-Car AC System Parts

  1. Car AC Compressor:
  2. Car AC Condenser:
  3. Car AC Receiver Drier:
  4. Car AC Accumulator:
  5. Car AC Expansion Valve:
  6. Car AC Orifice Tube:
  7. Car AC Evaporator:

1. Car AC Compressor:

Car Air Conditioner Compressor a part of car ac system
Car Air Conditioner Compressor

The car AC compressor is the most important car AC system part and the heart of the air conditioning system. Without a compressor the whole system is useless.

A compressor as its name suggests that it compresses refrigerant (remember it compresses only gaseous refrigerant, not liquid refrigerant). It compresses low-pressure refrigerant that comes from an evaporator and makes it into a high-pressure state causing it to liquefy. Undoubtedly, it increases both its temperature and pressure.

AC compressor consists of a free-spinning pulley, magnetic clutch, and electromagnetic coil. A compressor is powered by a crankshaft-driven belt. The compressor uses a magnetic clutch to connect and disconnect the compressor from the engine.

When you push the AC button, the electromagnetic coil is activated. Which attracts the magnetic clutch to a pulley, and rotates together as one assembly resulting in compressing the refrigerant, and pushing it into the condenser.

Sometimes a worn belt will cause the AC compressor to NOT function properly. if a compressor leaks from the central “O” ring and is also seized, will make a clicking noise. Better to replace it.

Related Post: Types Of Compressor Oil: Mineral, PAO, POE, PAG Oil, & Purposes

2. Car AC Condenser:


A car AC condenser is an essential car AC component used to condense gaseous refrigerant that comes from the evaporator into a liquid refrigerant by dissipating heat from it. Now here is the important question what does a car AC condenser do?

The answer is, that the car AC condenser is a large heat exchanger, unlike an evaporator, which absorbs heat. It releases heat from the refrigerant by driving fresh air across the condenser through the condenser cooling fan or by natural flow while driving.

A radiator’s job is to release heat from the engine coolant, while a condenser’s job is to release heat from the AC refrigerant.

In the whole AC system, the condenser is more prone to physical damage than any other part because of its frontal location. It is made of aluminum, located in front of the radiator, and looks the same as the radiator but is a little thinner in size.

Damaged Condenser
Damaged Condenser

Small stones, dust, leaves, and other objects on the road can hit the condenser leading to leaks and corrosion. A condenser can also be susceptible to internal damage.

Debris can add up in the condenser’s small tubes, which block the flow of refrigerant. A damaged AC condenser should be replaced, not repaired.

Related Post: How Car Air Conditioner Works (Animation): Science-Based

3. Car AC Receiver Drier:

Receiver Driers a part of car ac system
Receiver Driers

Also called a filter drier. It is an important car AC part. A car AC receiver drier is a metal canister containing desiccant (A substance that absorbs water) and a filter with an inlet and outlet ports.

It is located in a high-pressure line in the AC system between the condenser outlet and expansion valve inlet. When the refrigerant leaves the condenser and passes through the receiver drier.

It cleans the refrigerant and makes it perfect for metering operations. The receiver drier has three main purposes which are mentioned below.

Functions Of The Car AC Receiver Drier

1. Acts As A Storage Container:

The car AC receiver drier acts as a short-term storage tank for oil and refrigerant.

2. Acts As A Cleaner:

The car AC receiver drier acts as a filter. It filters debris and impurities from the refrigerant in the AC system.

3. Acts As A Drying Agent

The car AC receiver drier acts as a cleaner. Inside a receiver drier, there is a desiccant that absorbs moisture from the refrigerant. Moisture can get into the car’s air conditioning system from humidity in the air during manufacturing or service.

If moisture is not removed from the system, it can become ice crystals and lead to blockage and mechanical damage.

The receiver drier stores a short amount of moisture. If the receiver drier became defective and shows the symptoms of a leak, clogged, or hear a rattling noise.

You should replace the receiver-drier. Also when a compressor is replaced or the system is retrofitted, you should also replace the receiver-drier.

Related Post: Refrigerant Is Filtered Via Receiver Drier

4. Car AC Accumulator:

Accumulator a part of car ac system

The car AC accumulator is an important car AC system component. It is much like in purpose to receiver drier. It is a metal canister filled with desiccant and filter.

But the main difference is that the car AC accumulator is larger in size than the receiver drier. It is located in a low-pressure line between the evaporator outlet port and the compressor inlet port. You should remember that AC accumulators are only used with an orifice tube system.

Accumulator does the same job as the receiver drier does. It filters absorbs debris and moisture and also stores liquid refrigerant that comes from the evaporator to the compressor.

You might be wondering by knowing that an orifice tube cannot fully convert liquid refrigerant to vapor refrigerant, which causes compressor damage.

For this purpose, the accumulator is installed before the compressor to store the liquid refrigerant for a while. As the compressor is only designed to compress the gaseous refrigerant, not liquid refrigerant.

Accumulator a part of car ac system
Accumulator (Source agcoauto.com)

Accumulator stores liquid refrigerant at the bottom, which the compressor cannot suck. The liquid refrigerant gradually vaporizes Off. The vapor refrigerant rises to the top and continues to go to the compressor. These vapors then enter the compressor where it is recycled in the compressor.

5. Car AC Expansion Valve:

Expansion Valve a part of car ac system
Expansion Valve

The car AC expansion valve is an important car AC part, located in the inlet of the evaporator. It is the boundary between high-pressure and low-pressure lines in air conditioning. It is the expansion valve that creates a cooling effect in the refrigerant.

The expansion valve as its name suggests that it expands the refrigerant. You will feel the air cools in a short amount of time, this is due to the rapid expansion of the refrigerant.

In the evaporator, the refrigerant is spread out in a relatively large area. This expansion causes its pressure and temperature to rapidly drop, resulting in a cooler evaporator.

The car AC expansion valve converts refrigerant from the liquid state to the vapor state by spraying a small portion of refrigerant into the evaporator. In other words, it controls refrigerant flow by limiting pressure, which is also called “Metering”. A movable rod that moves back and forth in the inside expansion valve permits the refrigerant to go and stop.

Related Post: 7 Reasons Your Car Stalls/Shuts Off When AC Is Turned ON

Symptoms Of A Bad Car AC Expansion Valve

Warm air or frost coming out from the vents or the AC system is always ON is the symptom of a bad car AC expansion valve.

6. Car AC Orifice Tube:

Orifice Tube a part of car ac system
Orifice Tube

The car AC orifice tube is also an important car AC system part. It is an alternative to the Expansion valve. It is used in the system where the expansion valve doesn’t use.

The car AC orifice tube is located often in the condenser outlet. It divides both high and low-pressure systems. The car ac orifice works the same way as the expansion valve does. It changes the refrigerant from a liquid state to a vapor state.

But the major difference is, that the expansion valve has a movable rod that controls the refrigerant flow. Whereas an orifice tube has no movable part. It cannot control the amount of refrigerant passing through it and has a fine fixed hole restriction through which refrigerant passes.

The car AC orifice tube cannot alter the refrigerant flow speed the way the expansion valve does. To vary the refrigerant flow speed it depends solely on the compressor to turn ON and OFF and also on the regulating valve fitted in the compressor.

A filter is located on the inlet side of the orifice tube to filter the debris. These debris and metal particles can sometimes clog the orifice tube.

Remember one important thing in an expansion valve system, the receiver-drier is used with the expansion valve. Whereas in the orifice tube system, the accumulator is used with an orifice tube.

Related Post: Clogged Expansion Valve Or Orifice Tube

Signs Of Bad Car AC Orifice Tube

The symptom of a bad or defective car AC orifice tube is intermittent cooling or AC blowing cold air than warm air, and abnormal pressure reading like low side-pressure reading below normal reading or high side pressure reading above the normal high-pressure reading.

7. Car AC Evaporator:


The car AC evaporator is the most important car AC system part. It is the same as the radiator buried deeply hidden inside the dashboard in the driver/passenger compartment.

The car AC evaporator is a component where evaporation happens. In other words, the car AC evaporator is a car AC part where liquid converts to vapors.

It consists of a series of tubes with fins made from aluminum because aluminum is a good conductor.


The evaporator is a heat exchanger. It adds heat to air-conditioning refrigerant by passing warm air across the evaporator using a blower motor inside the cabin and making the inside air cool. It also dehumidifies the air.

Now here is the interesting part that why dehumidification is necessary. Let me break this down for you.

You might know that heat remains more in humid air than in dry air because humid air contains more water molecules. That is why when the air is drawn across the evaporator, water molecules condense at the surface of the evaporator and drip out of the vehicle through a drain pipe making the air dry. This increases the effect of coolness.

Some vehicles have two evaporators. One is under the dashboard and the second one is located in the rear section behind a side panel or the ceiling above the rear passenger.

Signs Of Damaged Car AC Evaporator

The biggest sign of a defective car AC evaporator is Leakage. Other signs are weak cool air, strange odor and even the compressor will not turn ON.

Heat Remains More in Humid Air Than in Dry Air.

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    2 thoughts on “7 Basic Parts of Car AC System (With Pics) & Their Functions”

    1. Norman A. Rivera

      I like your presentation and agree with much of this information. I learned some basic parts of the air conditioning system of a car after reading this article.

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