Why is the A/C in My Car Not Blowing Cold?

You get in your car in the middle of the summer, turn it on and leave your house. The air conditioning has been on for a few minutes but is still not blowing cold. You roll your windows down, but by the time you get to your destination, you are covered in sweat. Dealing with this every time you drive during the summer gets old quickly. But why is your A/C suddenly not blowing cold? Automotive air conditioning systems are complex and have many components that can fail. We are going to go over the most common causes of automotive air conditioning failure.

Why is my A/C not working in my car?

Graphic explaining air conditioning system

The air conditioning in your car is a closed system and must remain sealed to function properly. A breach in the system or failure of a component will reduce the effectiveness of the air conditioning, resulting in warm air coming through the vents. Below are the five most common causes of poorly functioning vehicle air conditioning.

1. Leaking or low AC refrigerant

Over time the closed and pressurized A/C system in your vehicle may start to leak. With less refrigerant, the system’s ability to cool the air entering the cabin decreases. In theory, without a leak, the refrigerant level in the air conditioning system would not change. If you notice warm or hot air coming through the vents in your car, recharging the A/C can help it blow cold again. Many repair shops can recharge your A/C system through the low-pressure port of your A/C system.

It can be tempting to buy a recharge kit from a local auto parts store, but without the proper training or tools attempting to recharge your A/C yourself can cause further damage to the system. Tracking down the leak responsible for your lack of refrigerant is also best left to the pros, as locating it can be an extremely time-consuming and tedious diagnostics process.

2. Bad air conditioning compressor

a/c compressor in car

The A/C compressor pressurizes the refrigerant into a gas. Your air conditioning system is powered by the compressor. If the compressor fails, the refrigerant will be unable to cycle through the system, meaning the air entering the cabin will not be cold. A sudden change in air temperature coming through the vents could indicate a failed or failing A/C compressor. 

There are a few reasons your A/C compressor could have failed, such as a bad compressor clutch or various electrical issues.

3. Blocked or broken condenser

The A/C condenser allows the gas created by the compressor to change forms into a high-pressure liquid. Additionally, it helps remove heat from the refrigerant before it heads through the compressor again. The condenser is located at the front of the car, meaning it can become damaged or blocked by debris while driving. In addition to causing warm air to come through the vents, a damaged A/C condenser can cause overheating, emitting a burning smell when the A/C is on. 

4. Broken air conditioning fans

air conditioning fan

The air conditioning fans assist the condenser in changing the state of the refrigerant from a gas to a liquid. If the fans are not working, the refrigerant will not be as efficient at cooling the air coming into the cabin. It is relatively easy to check the A/C fans on most cars. Pop the hood when the vehicle is running and look at the front of the car, near the radiator. If the fans are not moving while the A/C is on and the air coming through the vents is warm, they may be broken. 

Some common reasons for a faulty A/C fan include a blown fuse, bad relay, bad wire, or physical blockage preventing it from spinning at the proper speed.

5. Clogged Cabin Air Filter

Your car’s cabin air filter is responsible for filtering contaminants and debris from your interior and climate control system. However, after the filter has caught a significant amount of this dust, dirt, and pollen, it can become blocked and restrict the amount of airflow entering the system.

Without the proper amount of air being pulled through, your A/C will be less effective at delivering cold air into your interior. Luckily, cabin air filters are generally one of the easiest and least expensive maintenance items to take care of.

What should I do when my car A/C is blowing warm air?

The best thing to do if you notice your A/C is not working as it should be is to bring your car to a qualified shop. The complexity of most vehicle air conditioning systems makes it difficult for the average person to figure out what is exactly wrong and could cause further damage if done improperly.

Take note of when you noticed the issue started, any odd smells or noises, and any recent accidents or other factors that could potentially impact your air conditioning. When you bring your car in, pass this information on to your service advisor. 

How can I extend the life of my air conditioning system?

Here are a few steps you can take to help ensure the longest lifespan possible for the components and refrigerant within your vehicle’s A/C!

  • Minimize dust and dirt in your interior to prevent contamination
  • Ensure proper coolant level as this can cause harm to A/C components
  • Keep an eye on your refrigerant charge
  • Run your A/C on defroster mode weekly (especially during the winter) to prevent seizing
  • Regular cabin air filter replacements
  • Try not to overdo it with A/C

Get your car’s AC repaired

If you have issues with your air conditioning, call or schedule an appointment at Becker Service Center! The team of skilled ASE-certified technicians at our Naperville repair shop will get to the bottom of your air conditioning issue quickly, keeping you cool this summer.