The Top 3 Reasons Your Car’s A/C Isn’t Working

By Kimberlea Buczeke - June 29th 2017

Summer is in full force and your car’s air conditioning is going to be totally essential to your driving comfort. We’ve all tried to drive in a car with broken A/C before, and it’s not a pleasant experience – nobody wants to get in their car and feel like they’re stuck in a sweat lodge.

So it’s time to check on your car’s air conditioning system and make sure that everything is still in working order. Get in there, crank up the A/C, and feel the breeze. Or maybe no breeze. Or maybe there's a breeze but it's blowing hot. Yikes!

We went ahead and put together some of the top reasons air conditionings fail us – check it out below and see if one of these might be your problem.

Image Courtesy of Pixabay

1. Your Car Is Running Low On Refrigerant

If there’s plenty of air blowing through the vents of your car’s A/C, but it isn’t cold, this is likely the culprit. Either you have a leak in the refrigerant system, or the refrigerant in your car’s A/C has simply not been replaced for an extended period of time.

A great way to check for low refrigerant is to listen to your A/C compressor. When there is plenty of refrigerant in the compressor, you’ll hear a “click” when you turn on the A/C. If your system is low on refrigerant, it will cycle on and off repeatedly, attempting to get enough refrigerant into the system to cool the air. And if you have a very low level of refrigerant left, the compressor will fail to turn on at all. 

To fix this issue, leaks must be found and fixed if present, and then your refrigerant must be “recharged," either on your own (beware!), or by a certified car repair technician

2. Your Compressor Is Failing

If you have found that your car has proper levels of refrigerant, but the A/C is still not functioning, your compressor is probably failing. The compressor is the “heart” of your car’s AC – literally, because it compresses and pumps the refrigerant throughout your A/C system, which allows the air to cool. 

There are several ways in which a compressor can fail – it’s possible that the compressor belt that transfers power to the compressor has failed, or that the electronic circuits controlling the compressor have failed. However, it is also possible for a compressor to simply wear out – in which case, it will need replacement.

a/c 2
Image Courtesy of Pixabay

3. Airflow From The Vents Is Blocked

This is an obvious – yet sometimes overlooked – issue when it comes to A/C in cars. There are three primary methods by which airflow is controlled in modern cars.

  • Cable operation – These are the simplest, least sophisticated control mechanisms, employing levers, knobs, cables, and cable-controlled flaps that control the opening and closing of the vents, as well as the angle of airflow. If the cables break, you may be unable to adjust your AC vents, and they may become stuck.
  • Vacuum operation – As the name suggests, these systems used vacuum-based motors that operate the doors and flaps. If the system loses vacuum through a leak, the airflow will be redirected to the windshield, meaning you won’t get good A/C airflow.
  • Electrical operation – These are more common on modern cars with features like driver/passenger side A/C, and use electrically controlled systems to send signals to electric motors, which open and close the doors. Should these motors or control modules fail, the doors won’t open/close correctly. 

Whatever the cause, the repair will usually have to be conducted by a professional, as even the repair of cable operated vents requires special tools and expertise.

Beyond these mechanical issues, cabin air filter systems can cause low air flow if they are excessively dirty or grimy – this reduces the ability of the car to take in fresh air, resulting in lower airflow. Consider an air filter replacement if you haven’t replaced your cabin air filter in over 10,000 miles.

Understand How Your Car’s A/C Functions – And Take Necessary Steps to Get it Ready For The Warm Weather!

These are the three primary reasons that your car’s A/C may not be working correctly – and chances are that if you are having issues, they’re being caused by low refrigerant, a malfunctioning compressor, or blocked vents.

However, each car is different – so if you’re still having issues (or your issues don’t match the ones listed above) we recommend bringing your car in for an A/C assessment to a professional. For a reasonable price, you can easily get an inside look at the state of your car, and take further action as appropriate. Stay cool out there, folks!

RepairPal is working to mend the lack of trust consumers have in the car repair industry by providing them with in-depth knowledge and resources that connect them with dependable and reliable car repair shops near them.

Our goal is to establish an auto repair process that is less stressful and much more trustworthy for everyone involved. Our website hosts a car repair Estimator that gets rid of that "ripped-off" feeling. We also provide matches to local Certified shops that are guaranteed to do repairs with quality parts, a fair price, and a trained, awesome staff.

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3 User Comments

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hi l listened to hear the humming of the fate sound of the motor running and it does, the compressor works when I put in the refrigerated air and I also checked the ac united and that was fine. where could it be leaking.
Hey RamonaRose, that looks like a great question for our Q&A page. You can include details about your car and expand on exactly what's happening. Someone should be able to help you out! You can find that page here: – good luck!