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Summary
  • Air conditioning systems in vehicles are closed and sealed units wherein a belt-driven compressor circulates refrigerant throughout the system.
  • It’s a good idea to put up a sunshade on your windshield to prevent the temperature from rising too quickly inside the cabin.
  • Blasting the fan speed to its highest setting can help your car cool down faster. Leave the fan on the maximum speed setting for a few minutes until you notice a significant drop in temperature.

The heat can sometimes be unbearable. Imagine having to sit in your car for hours covered in sweat一all because your car’s air conditioning (A/C) system can’t seem to handle the heat. 

Fortunately, there are a few things you can do to make your car’s A/C colder without having to spend too much. 

What Makes the A/C Cold In Your Car?

First things first一how exactly does the air in your car get cold? 

making car ac blow colder air
Air conditioning in a vehicle is based on the principle stating “cold attracts heat.” If the evaporator is cold, it can attract hot air in the cabin.

Air conditioning systems in vehicles are closed and sealed units. They have a belt-driven compressor that circulates refrigerant throughout the system.

Refrigerant boils at around -20 degrees Fahrenheit, and as the refrigerant boils, it absorbs heat. It enters the evaporator (coming from the condenser as a hot high pressure liquid that then passes through the orifice or expansion valve so that it becomes a low pressure liquid). It enters the evaporator (a heat exchanger, sort of like a radiator) and proceeds to turn to a low pressure gas as the warm outside air passes through the evaporator fins where the refrigerant is flowing.

Thus, the air leaving the evaporator is much colder than it was when it entered the other side of that heat exchanger. This only works when the compressor is operating.

When the refrigerant leaves the evaporator as a low pressure gas, it is very cold and travels to the compressor, where it is squeezed into a high pressure gas and sent to the condenser, where it releases the heat it picked up in the evaporator. It then leaves the condenser and makes another trip through the evaporator.

The air that is being cooled can come either from outside (norm) or inside the vehicle (max/recirc).

So, to put it another way, the refrigeration cycle converts liquid into gas, which absorbs heat as it changes to gas, which naturally absorbs the heat from inside the vehicle.

Air conditioning in a vehicle is based on the principle stating “cold attracts heat.” If the evaporator is cold, it can attract hot air in the cabin. Cold doesn’t move; cold is only the absence of heat.
Based on the principle, heat always travels toward the cold; think of anything cold as a “heat vacuum,” which naturally fills with heat. So when hot air passes through the evaporator, the evaporator absorbs the heat, lowering air temperature in the process.

The cooled air is then directed towards the passenger compartment by the blower through the air conditioning vents.

How to Make a Car’s Air Cooler

There might be instances where turning a simple knob on your A/C unit won’t be enough to cool your car down. Here are some things you can do to make the cabin cooler. 

Park In the Shade

Leaving your car to cook under the scorching heat can make the cabin hot enough for you to get torched when you hop on your seat or touch the steering wheel. 

That being said, try to find a shaded area to park in whenever possible. It’s also a good idea to put a sunshade on your windshield to prevent the temperature from rising too quickly inside the cabin. Note that the sunshade will help some, but not much.

Lower The Windows For a Minute or Two

Blowing the heat out of the cabin by lowering the windows will help a lot. Some vans have power rear quarter windows that open at the rear to assist in purging hot air from the cabin.

Blast the Fan and Recirculate

Blasting the fan speed to its highest setting can help your car cool down faster. Leave the fan on the maximum speed setting for a few minutes until you notice a significant drop in temperature. 

After a few minutes, you can reduce the fan speed and turn on the air conditioner along with the recirculation mode. 

The recirculation feature closes off the hot air from outside and recirculates the cool air inside the cabin, which can bring down the cabin temperature faster.

, How to Make Your Car’s A/C Colder

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Incidentally, on a trip, running the A/C on recirc (max) helps with fuel economy because the compressor doesn’t run as much. It takes more compressor operation to cool outside air coming in than it does to cool air that is being recirculated.

Avoid Playing with the Knobs and Buttons

Leave the temperature dial on the coldest setting, and adjust the fan speed as needed. The air at the registers will be colder on low fan speed than on high fan speed, and when the vehicle is moving the A/C will work more efficiently due to better airflow across the condenser.

The air at the registers will be colder on low fan speed than on high fan speed, and when the vehicle is moving the A/C will work more efficiently due to better airflow across the A/C condenser.

Richard McCuistian, ASE Certified Master Automobile Technician
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Don’t Forget to Service These Air Conditioning Parts 

If you want to keep your car cool for a long time, you should know that the previous tips mentioned won’t get you that far without the proper system maintenance. 

Don’t forget to service these air conditioning parts to ensure that your A/C system will run smoothly. 

Cabin Air Filter (if equipped)

The cabin air filter traps contaminants from the outside air so that clean air can enter the passenger compartment. Most manufacturers recommend replacing the air filter every year or 12,000 miles. Failure to replace the filter can result in clogs, which can affect engine efficiency. 

 Note that many vehicles, even newer ones, won’t have cabin air filters.

Compressor

The compressor is responsible for pumping refrigerant throughout the air conditioning system. A faulty compressor can prevent refrigerant circulation, resulting in warm air output from the vents. In addition to the compressor’s mechanical components, there are some fairly involved electronics that cause the compressor to energize, so don’t discount the idea that something electrical may be wrong that’s causing the compressor not to energize.

If your vehicle has enough refrigerant but is displaying signs of poor A/C performance, a faulty compressor is usually to blame.

However, since there is no dipstick for refrigerant, you won’t know if your refrigerant is low or not, and simply adding more may make the problem worse if the issue is somewhere else. Adding refrigerant when the system is already full can cause issues while not fixing anything.

Condenser

In a normal air conditioning refrigeration cycle, the liquid refrigerant evaporates into a low-pressure gas. After the compressor compresses the gas into its high-pressure state, it flows into the condenser.

The condenser looks like a radiator and has a similar function. It is designed to remove heat from the high-pressure gas. The high-pressure gas turns into a high-pressure liquid, and the heat from the refrigerant is released into the atmosphere.

Most A/C condensers fail due to leaky seals, which may become common as your vehicle ages. An A/C condenser can also fail because of debris buildup.

Straw and plant material can pass through the condenser only to be trapped between the condenser and the radiator. This will interrupt airflow and cause high pressure issues and loss of cooling, both of the engine and the A/C system.

, How to Make Your Car’s A/C Colder

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: A bad condenser fan or one that only works sometimes is another issue to watch for, particularly if the A/C cools good on the road but not in traffic or at the drive thru. Of course, it’ll naturally cool a bit better on the road anyway than it will when sitting still, but it should still cool. Don’t sit too near the car in front of you in traffic, either. Exhaust pipe heat from that car can cause issues if it’s making its way through your condenser.

A/C condenser-related problems can prevent the air from getting cold. You might also notice refrigerant leaks from underneath your vehicle.

Worse comes to worst, a faulty A/C condenser can prevent the radiator from cooling down, resulting in an overheated engine.

The Importance of A/C System Maintenance

Your vehicle’s air conditioning system won’t need as much maintenance as the engine and transmission, mainly because it’s a sealed unit.

Other than replacing a dirty air filter and topping up on refrigerant, you won’t need to think about the air conditioning system unless something malfunctions.

It’s important to note that once a component fails, you should have your vehicle serviced right away. Leaving a problem unaddressed for too long can create bigger issues and damage other critical parts in your air conditioning unit.

Instead of replacing a leaky hose, you could end up buying a new condenser, which costs a lot more money than a rubber tube.

You also wouldn’t want to keep driving with an A/C unit that blows warm air under the summer heat.

Here are 3 more tips on A/C maintenance:

  1. Try not to sit still in a parking lot running the A/C for a long period of time if you can help it.
  2. A/C leaks never fix themselves, and stop leak only causes more problems.
  3. Never vent refrigerant to the atmosphere. It’s illegal and unnecessary.

Key Takeaways

There are several ways you can keep your car cool without installing anything fancy or having your vehicle serviced.

Parking under a shade, blasting the fan, and replacing the cabin filter are some of the things you can do to make your car’s air conditioning unit blow cool air faster than normal.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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