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9 Reasons Your Car AC Is Not Working Properly

Published Wed August 16, 2023

Lady sweating in her car


When temperatures start to rise, few things are more frustrating than getting into a car without a functional air conditioner. If you find yourself in this situation, be aware that your car’s AC may not work as it should for several reasons. By identifying the underlying causes of a malfunctioning system, you can discover why your car AC is not working and find the right solutions to keep you cool and comfortable on the road. 



What Causes the AC Not to Work in a Car?


Many factors can cause a car’s AC to not work properly, including mechanical failure, filter problems, a car AC leak, damage to the system, or disruptions with any parts or components related to the AC system. Often, what causes the AC to not work in your car can be simple to identify if you know what to look for. Make a note of the AC problems you experience, which may include the system: 


  • Blowing warm or hot air, even with the cold air turned up
  • Blowing cold air only under certain conditions
  • Working intermittently
  • Failing to turn on completely

Making sure your AC system is in good working condition is important for comfort, plus the health and safety of you and your passengers. Investigating the reason behind your car’s AC failure is the first step in troubleshooting the issue.



9 Common AC Problems 


If your car AC is not working the way it should, it could be caused by one of these common AC problems.


1. Clogged Cabin Filter


Your car’s cabin air filter helps to keep the air in the vehicle clean and free from dust, pollen, and other pollutants. Over time, these particles can accumulate in the filter and obstruct the air passage. 


When the cabin air filter gets clogged or hasn’t been replaced recently, it restricts airflow and causes your AC system to work harder than it should. Replacing or cleaning the air cabin filter can increase cooling efficiency and improve your car’s AC performance. 


2. Low Refrigerant


Without refrigerant, your car cannot circulate cold air throughout the cabin. Refrigerants are crucial for regulating the air that comes through your AC system to a nice, comfortable temperature.


Insufficient refrigerant levels can hinder the cooling process, so only warm air blows from the vents. Since your AC is a closed system—meaning there is no need to “top off” refrigerant over time—low levels typically indicate it’s time for an AC performance test and checkup since it may suggest a leak. 


3. AC Leak


Your car’s AC system has several different components that pass or condition the air so it cools down. Any leaks in the system’s hoses, O-rings, or seals can reduce cooling efficiency. Not only this but leaving a leak unaddressed can lead to bigger problems down the road. 


Car AC leaks are one of the most common AC problems. They can be caused by accidents or collisions, cracks in the system, improper maintenance, or clogs that can cause pressure to build in the system and compromise the components. It can be challenging to identify a leak on your own, but professional diagnostics can quickly identify a potential leak in your system. 


4. Broken Fans


Like any other component of your car, the fans in your AC system can break or malfunction after a while. If they do, it can significantly reduce the effectiveness of the AC system overall by restricting or halting airflow. 


Sometimes, the AC fan works perfectly well only to stop working for no apparent reason—and work perfectly again the next day. This may not be a problem with the fan itself. Instead it could be an electrical issue, a problem with the blower motor, or burnt-out system components that impact the way the fan functions. 


5. Compressor Issues


The AC compressor is responsible for pressurizing and circulating refrigerant in the system. It does this by shifting the air pressure during the cooling process, helping to create the ideal environment in the system to transfer heat energy away from the cabin and allow cold air to circulate. 


If the compressor is faulty or won’t work properly, the AC system cannot cool the airflow efficiently. There may be problems with the AC compressor if you hear odd noises near the engine, only feel warm or hot air, or see visible damage to any compressor parts.


6. Electrical Problems


There are many electrical parts involved in your car’s AC system. Problems with the wiring, the breaker, or the capacitor can result in electrical issues for your car’s AC. Fortunately, you can troubleshoot some of these if you suspect it’s an electrical issue. 


If your AC system seems to have trouble starting up, turns on and off at regular intervals, or seems to have problems with power trips, it could mean a problem with the electrical system. This could be as simple as a damaged wire or a bad fuse. 


7. Faulty Pressure Switch


The pressure switch monitors pressure levels in the AC system and ensures the refrigerant remains stable. If refrigerant pressure gets too high or low, it can restrict the function of, or even damage, the compressor. 


A defective pressure switch can also prevent the compressor from engaging at all. This can result in only warm air coming through the vents. You may need a pressure switch replacement if the AC system only functions some days and not others or if it won’t seem to turn on. 


8. Sensor Problems


Various sensors in your car’s AC system detect temperature and operational changes and trigger the system to react by starting, stopping, or slowing down operations. Faulty sensors can cause inaccurate temperature readings, which may cause the system to function improperly. 


If these sensors fail, it can impact whether other components can do their job to cool the airflow in the cabin. Sensor problems often look like unexplained air temperature fluctuations or a lack of cold coming through the system. 


9. Damaged Head Unit or Controls


The head unit refers to the area inside the cabin that allows you to control the temperature, fan speed, and air conditioning mode. Issues with the AC controls or the head unit can lead to problems with temperature regulation, which often causes an inability to effectively communicate with other components of the AC system. 


The buttons and knobs of the controls may be loose, damaged, or unresponsive. In this case, it’s vital to have them repaired or replaced by a qualified technician. 



Restore Your Car’s AC System


There are many reasons to explain why your car AC is not working correctly. If you’re experiencing any of these common AC problems, take steps today to get your system working like new. Properly diagnosing and repairing AC issues requires expertise and specialized tools. Your car is in good hands when you bring it to Meineke. Don’t suffer in the heat any longer. Schedule a professional inspection and AC repair service at a Meineke location near you.