How does air conditioning work in a car?

5 minute read Published on Mar 24, 2024 by BrokerLink Communications

Young auto mechanic refueling car AC in a repair shop.

If you drive a car in Canada, you should know a few things. First, you should understand what mandatory car insurance looks like. Second, you should know how to be a safe driver, and third, you should know how your car works, including your vehicle’s air conditioning (AC) system. Below, we dive into all things car AC, including how these systems work, the essential parts they are made up of, and how to detect when something’s wrong.

Car air conditioning explained

Most modern cars have air conditioning systems, yet you may have no idea how your system works. The reality is the cool air that comes out of a car’s vents when you turn the air conditioner on is actually hot air that has had the heat removed during a complex process.

The process looks something like this: When the air conditioning system is turned on, the compressor compresses the refrigerant, a fluid used in AC to absorb heat and then releases it, increasing its pressure and temperature.

As the refrigerant flows through the condenser, it loses heat. Next, the refrigerant passes through the receiver or dryer, during which any moisture is removed. After that, the fluid makes its way to the expansion valve, where it loses pressure, resulting in a drop in temperature before entering the evaporator.

The evaporator is the final step in the AC process and functions as a small radiator in your car's dashboard. Air gets blown through the evaporator, which then cools and removes the last of the moisture from the air. This allows the ventilation system in your vehicle to blow cool, dry air into the passenger area of your car, cooling off drivers and passengers alike.

Please note that purchasing car insurance can help cover the cost of repairing a broken air conditioning system if it is damaged in an accident. You can receive a free quote or find out how much car insurance costs per month in Ontario by contacting BrokerLink today.

The parts of a car’s air conditioning system

Are you ready to receive an in-depth look into your car’s air conditioning system? Keep reading to learn more about the elements that allow your car’s AC to work the way it does:

The high-pressure side

First up is the high-pressure side. Think of your car’s air conditioner as a fully closed loop containing high-pressure and low-pressure sides. The high-pressure side is what involves the engine to the passenger compartment and includes the following parts:


The compressor is a type of pump that runs via a belt attached to the engine's crankshaft. During AC, the refrigerant flows into the compressor as a low-pressure gas. Once the gas is in the compressor, it is put under an extremely high amount of pressure, forcing it out into the condenser. Please note that compressors are only able to compress gasses, not liquids.


The condenser is the second part of the high-pressure side of an AC system. As mentioned above, it acts as a radiator, primarily to remove heat from the air conditioning system. How does it do this? The refrigerant enters the condenser as a high-pressure gas after coming out of the compressor. As the gas moves into the condenser, it heats up but flows through the tubes of the condenser and cools it down, forcing it to change state once again, this time from a gas to a high-pressure liquid.


The receiver-dryer is the final component of the high-pressure side of your vehicle’s air conditioner. Once the liquid is done with the condenser, it goes to the receiver dryer. In the receiver-dryer, water is removed by the desiccants that it contains, which is what allows it to turn into cool air. Without this step in the process, moisture would remain in the system and cause it to break down.

The low-pressure side

Once the cooled liquid has been prepared by the high-pressure side of the AC system, it’s time to move on to the low-pressure side. The low-pressure side involves the following:

Thermal expansion valve

The low-pressure side of the air conditioner in your vehicle begins with the thermal expansion valve, which is where the temperature of the refrigerant goes from a high-pressure, high-temperature liquid to a low one. In other words, the thermal expansion valve is responsible for changing the temperature of the liquid from hot to cold. After flowing in from the receiver-dryer, the liquid expands in the expansion valve, which decreases the pressure.


Once the pressure has gone down, the liquid enters the evaporator. Unlike the other AC components mentioned thus far, the evaporator is in the cabin rather than the engine compartment. Evaporators look almost like radiators, featuring a coil of tubes and fins. However, unlike a radiator, an evaporator’s job in an air conditioning system is to absorb heat instead of disseminate it.

At this point, the refrigerant is typically entering the evaporator coil as a cold, low-pressure liquid. A fan is responsible for blowing over the evaporator coil, which results in cool air entering your car. In essence, the gas leaves the evaporator and then comes out of the vents in the vehicle's passenger compartment, removing the heat in the process.

Finally, the refrigerant - now a gas - enters the compressor to start the process all over again. Ultimately, the AC works in your car through a loop system.

The most common issues with air conditioning systems in cars

A few of the most common problems that occur in car air conditioning systems are as follows:

  • Refrigerant leak
  • Blocked or clogged condenser
  • Faulty compressor
  • Broken cooling fan
  • Electrical issues

Given how many things can go wrong, experts recommend maintaining and servicing your car regularly. A BrokerLink insurance advisor can provide a wide range of summer and winter car maintenance tips and explain other ways to protect your vehicle year-round, such as with snow tires for winter drivers.

Get in touch with BrokerLink

If you still have questions about how air conditioners work in cars, contact BrokerLink today. We can provide more insight into the AC process and help you find a quality insurance policy that will protect you in the event of an air conditioning leak. For example, there are many types of auto insurance, such as third-party liability car insurance, that could cover you for the cost of AC repairs. Other types of car insurance that may be worth adding to your policy include:

Request a free insurance quote today and receive free tips from a licensed broker at BrokerLink. We can offer all sorts of advice on everything from tips for driving on icy roads to steps to take if you’re trapped in a vehicle in the snow.

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