Updated at: 04-04-2023 - By: Helen Skeates

Do you want to know how an automobile’s air conditioning system operates? Don’t go anywhere just yet. Instead, the question will be addressed here. Car air conditioners cool the cabin by cycling air back and forth, a process facilitated by the heat exchange mechanism provided by the air conditioner’s refrigerant. That which is conventionally found in homes, including air conditioners. I think that’s the end of the discussion. You’re prepared, I know it. Read the article and get in the saddle.


A Comfortable Drive

Comfort is the most noticeable advantage of using the air conditioner in your car. If you turn on the air conditioning, you won’t have to suffer through the oppressive heat of driving in the summer. Instead of cranking up the volume by opening the windows, you may listen to your favorite tunes while staying cool with the air conditioner.

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Better Safety

Safer driving conditions are another benefit of keeping the air conditioner on. To begin, you won’t experience the fatigue that typically comes with being too hot. Inhaling cleaner, cooler air from the air conditioner is a surefire way to stay alert and focused.

Second, the windshield mist can be diminished by using the air conditioner. If your car is damp inside, turning on the air conditioner will quickly remove any moisture from the windscreen, allowing you to safely drive away from the garage.


Worse Fuel Economy

The most well-known drawback of automotive air conditioning is the decrease in gas mileage it causes. Saving money is as easy as turning off the air conditioner on short trips and rolling down the windows, as the AC uses fuel to run and can raise your fuel usage by as much as 20%. In the end, it can be a money-saver.

Steps On How Car Air Conditioner Work

Perhaps you’ve wondered, “how does an automobile air conditioner function?” I can sense your excitement at this prospect. In most vehicles, the air conditioner uses a refrigerant to exchange heat with the surrounding air, cooling the inside.

The first step in the air conditioning process is the introduction of a refrigerant. It plays an intermediary role in the heat exchange process in your car and has a low boiling point. Your vehicle’s interior air can be cooled down in seven simple steps. Here they are.

Step #1. Compressing things up

The compressor will begin operating as soon as the automobile is started. Here, the refrigerant is compressed and pressurized in preparation for use in the cooling unit. The compressed liquid refrigerant is then utilised by the air conditioner’s coils.

The compressor plays a crucial role in your car’s air conditioning system. Using this device, the refrigerant can be compressed into a liquid state. Liquid refrigerant is the lifeblood of the air conditioner. It does a good job of dissipating ambient heat.

Step #2. Refrigerant is on the move

The condenser’s coils are where the refrigerant will next make its way. At this stage, the liquid, compressed refrigerant in the coils reacts with the outside air. The air outside the condenser will be at a lower temperature than the fluid inside, creating a temperature gradient. After then, the high-temperature fluid’s heat will be released into the environment, where it will be absorbed by the ambient air.

Step #3. The receiver drier

Now the refrigerant enters the receiver dryer, sometimes called an accumulator. You may use this drier to keep your car’s air conditioning system in tip-top shape. The remaining fluids are converted into gas and sent to the compressor.

Moisture will be absorbed by a desiccant or similar substance in the receiver drier. Both the air and the refrigerant will be dried out by this apparatus. The refrigerant can be cooled, and the cooling system can keep running.

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Step #4. The expansion valve

The existing refrigerant will be transferred into the expansion valve in the form of a chilled fluid. The expansion of the refrigerant is regulated by this valve or orifice tube. Furthermore, it lowers the pressure that the refrigerant is exposed to before entering the evaporator. The fluid pressure will be lowered and the evaporator will get the refrigerant as a result of this procedure.

Step #5. The evaporator

The evaporator receives the refrigerant at this stage. At this stage, the vehicle is drawing air into the evaporator from all around it. Because of this, the refrigerant can be cooled down further and used to produce cold air for the vehicle’s cabin. The evaporator is responsible for absorbing the vehicle’s thermal energy and condensing it into a liquid refrigerant. You may see this component behind the air vents in your car.

Step #6. The highlight

After the evaporator, the cold air is pushed into the cabin by the vent fans. By doing this, you may get the proper level of cooling from your car’s air conditioner. Humidity and moisture within the automobile are eliminated by the air conditioning system.

This ensures that the air inside the vehicle is dry and comfortable for everyone. Water is produced when the humidity inside a car is reduced. It will then be leaking under the automobile to its proper location. Water droplets can be seen on the car when it is parked or when the air conditioner is on.

The refrigerant inside the coils gets hotter when the air conditioner is already running and blowing cold air. The refrigerant can then be converted back into its gaseous state.

Step #7. The cycle goes on

When the car’s air conditioner is turned off after cooling the inside, the refrigerant will revert to its previous state. This refrigerant is recycled through the compressor again and again to cool the system. By doing so, the car’s air conditioner can quickly provide freshly cooled air through the vents.

How To Maintain Your Car’S Air Conditioner

Inspecting The A/C System & Keeping It Running

Vehicles driven in cooler northern areas should have their air conditioning systems run for around 10 minutes once a week even when the weather is mild. The oil will be pumped around the system, preserving the seals from drying out causing brittleness (which would cause the Freon to leak out.) To prevent musty odors from developing in the air chambers, it is a good idea to turn on the air conditioner every so often to dry them out (or worse).

In addition to the essentially periodic running of the system, you should inspect your air conditioner to head off any potential issues. In a lot of ways, this is something that anyone can do. The air conditioning condenser, which is situated in front of the radiator, is the first component of the cooling system to be examined. The condenser is responsible for transforming the gaseous Freon back into a liquid state (it condenses). Remove any obstructions, like a clogged bug screen, from the condenser to ensure proper airflow. Air conditioner performance will suffer if the condenser is obstructed. When cleaning the condenser, a garden hose fitted with a high-pressure nozzle is all that is needed.

Checking The Engine Fan And Fan Belt

Next on the list is inspecting the mechanical or electrical components of the engine fan. An electric radiator fan must be constantly spinning whenever the air conditioner is turned on. Without the fan operating, the pressure in the system can build up to dangerous levels, causing the hoses to burst and the Freon and oil to leak out. When the air conditioner is turned on, just one of the two electric fans (if present) needs to be spinning. If you’re driving and the temperature of the air coming out of the vents is low but rises noticeably when you let the engine idle, it’s likely that your cooling fan is broken.

If, on the other hand, you have a mechanical clutch fan with a thermostat at its core, that fan will tighten up and spin faster as air passes through the condenser and the radiator. Checking the fan clutch is easy and takes only a few minutes. Turn the fan by hand while the engine is cold and turned off. As it should, the fan should spin freely. Once the engine is hot, you will feel some resistance when you turn the crank. If the fan is loose and free to spin when the engine is heated, the fan clutch is probably broken. As mentioned in the previous paragraph, if the air from the vents is cold when driving but noticeably warmer when the engine is idling, this is a sign of a faulty clutch fan.

Checking the fan belt is next and is done visually. Inspect the underside of the belt for cracks. If cracks are found, the belt should be replaced. On older vehicles a belt tension gauge is needed when replacing the belt to prevent excessive pressure being allied to components being driven by the belt. This can cause premature failure of these driven items but is not a problem with newer vehicles that have a spring-loaded belt tensioner which applies the correct amount of tension to the belt.

Checking Operation

The following step, checking the fan belt visually, comes next. Check the belt’s underside for any signs of cracking. Belt replacement is required if cracks are discovered. In order to avoid applying unnecessary force to the components being driven by the belt, a belt tension gauge should be used when replacing the belt in older automobiles. This may lead to the early failure of the driven components, however modern automobiles feature a spring-loaded belt tensioner that ensures the belt is always properly tightened.

What You Do Need A Professional For

About 10%-15% of the Freon in air conditioners is typically lost each year. Here is where you should seek out the assistance of an expert. There is a recommended amount of Freon that should be present in every air conditioner. There should be a label somewhere on the radiator housing, the bottom of the hood, or the evaporator compartment. This label specifies the exact type and quantity of Freon (in ounces and pounds) that should be present in the system at all times. When Freon leaks out, it sometimes carries oil with it, making the leaking region easy to spot. Black or oily residue on a hose or fitting is a telltale sign of a leak. Finding leaks can also be done with the use of a leak detecting dye or an electronic leak detector.

If the system is only slightly low on Freon, topping it off is not a good idea. If you add too much Freon to a system, you could damage the compressor or cause the pressure in the system to rise so high that the hoses rupture. To properly recharge an air conditioning system, one must empty the entire system and then add the specified amount of refrigerant as shown on the tag. If you want to recharge your air conditioner, you’ll need a vacuum pump and a set of air conditioning gauges. Because water boils at a vacuum of 17 inches at sea level, increasing the vacuum pressure in a system beyond this point will result in the removal of moisture by boiling it. 20-30 minutes of continuous operation of the vacuum pump is recommended for completely drying up the area. In order to monitor the level of vacuum pressure, one of the gauges is a low-pressure vacuum gauge. After 20-30 minutes of purging the system, the technician flips a switch to see the low-pressure side of the vacuum gauge. They should check for leakage of vacuum in about five minutes. As a general rule, if a system can hold vacuum, it can also hold Freon.

DIY Recharge Kits?

Beware of the do it yourself recharge kits that can be purchased from most parts stores. You must remember that there may be other reasons besides the loss of Freon causing an air conditioner to be inoperative. What would happen if something else beyond low Freon was the cause of the system’ problems? If Freon is added to an already-full system, it can cause the destruction of the compressor because of liquid Freon entering it, or the system hoses themselves can burst. None of that is good.

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DIY recharge kits are available at most hardware stores, but they should be avoided at all costs. It’s important to keep in mind that a lack of Freon isn’t the only thing that might render an air conditioner useless. What would happen if the system’s issues weren’t due to low Freon but to something else entirely? By introducing liquid Freon into the compressor, overcharging the system can destroy it, and bursting hoses in the system pose a similar threat. No, that’s not a nice situation at all.

Is Dripping Water A Sign?

A running air conditioner will cause water to drip from under the car. Condensation forming on the evaporator after it has been disconnected from the passenger cabin. Condensation drains may be clogged if water enters the passenger side floor from above rather than below the car. Mold and fungus can grow in stagnant water and eventually block the drain or hose leading outside. The majority of the time, this will necessitate a cleanout from the undercarriage.

Finally, the question I get asked the most is, “Why does it take so long for the air to get cold?” The sun’s heat radiating off the dashboard is only one of several factors that could make this a problem even if the air conditioner is in good functioning order. The dashboard will need some time to cool down. Dehumidifying a car also improves its performance. This process also takes a few minutes, and the resulting drips can be seen on the car’s undercarriage. Finally, most modern automobiles contain a cabin air filter that, when clogged, limits the flow of air through the dashboard vents. This filter needs to be replaced several times a year.

It is wise to inspect and service your air conditioning system before you get to the heat of summer when shops that service air conditioners are backed up. Also, people tend to spend more money than necessary when they are overheated. Beware of shops that tell you that Freon wears out and needs to be replaced for that reason because it does not. Also, a lot of quick lube shops push recharging your air conditioner because it is an easy and profitable up-sell. The odds are they are just adding Freon and not doing a proper recharging procedure as described in this article.


It is recommended to check and service your air conditioner before the summer heat sets in and repair shops are full. Overheated persons also have a tendency to spend more money than is healthy. Avoid stores that insist Freon depletes with time and must be refilled often. Additionally, many fast lube services strongly recommend having your air conditioner recharged as an easy and lucrative up-sell. Chances are, they’re just topping off the system with Freon and not following the steps outlined here.