May 21, 2024

My Car AC Isn’t Blowing Cold Air! 8 Common Reasons It’s Not Working

It’s a hot day, and you’re stuck driving in heavy traffic. You switch on the air conditioning, ready for some relief, but the car AC isn’t blowing cold air! What’s the big deal?

Nobody wants their car AC to fail, especially on those hot summer days when you need it most. There are many possible reasons your car’s AC isn’t working correctly. We’ll walk you through eight common ones so you can try to diagnose the problem. We’ll also give you some ideas on how you can fix the issue at home—and what to do when it’s time to bring in the pros.


How Does an AC System Work?

To understand what parts of your AC system could fail, let’s first review how a basic AC system works. An AC system has five steps that it constantly runs through to get cold air into the car cabin.

Step 1: A compressor is a pump that pushes the refrigerant (a substance used to create cold temperatures in AC systems and refrigeration appliances) through the AC system loop. It compresses the gas, increasing the pressure.

Step 2: The refrigerant goes into the condenser. As air flows into the engine area, the condenser begins the refrigerant cooling process. This happens when the gaseous refrigerant condenses and turns into a liquid form.

Step 3: The refrigerant is pushed through a small opening into the evaporator. The pressure dramatically changes when it’s forced through, cooling the refrigerant.

Step 4: The now-cold liquid refrigerant is transferred into the evaporator, where it cools air. The cooled air is blown by fans into your car, giving you some relief during hot days.

Step 5: The liquid refrigerant is turned into a gas again as it cools the air and is sent back to the compressor where the whole process begins again.


8 Reasons Your AC Isn’t Working

There are eight common reasons that might explain why your AC isn’t blowing cold air in the car

1. Clogged Filters

Your cabin air filter prevents dirt, pollen, and other debris from entering the car. If the air filter is clogged, it won’t let air pass through as it should, resulting in a weak or nonexistent airflow.

2. Faulty Controls

It’s possible the controls in the car aren’t working because of faulty wiring (or bad electronic signals in the case of newer cars).

3. Low or Leaking Refrigerant

Your AC depends on refrigerant to complete the cooling process. A leak in the system can lead to low refrigerant, preventing your air from cooling as much as you want.

4. Damaged Condenser

The condenser sits right in front of your radiator. Since this important AC component is more directly at the mercy of the elements, it’s commonly blocked by leaves or other debris that have built up and clogged it. It could also simply be the victim of old age—they only last 10 years or so.

5. Faulty Sensors

Your car uses sensors to gauge the temperature inside the car. When you set your car’s desired temperature to a certain number, the sensors tell the AC system to turn on. If your sensors are damaged and can’t tell the temperature correctly, they won’t send the necessary signals to the AC system.

6. Pressure Switch Issues

Pressure switches in cars keep track of the state of refrigerant. If the pressure jumps into a red zone (too high or too low), the compressor automatically turns off for safety reasons, and the AC won’t work.

7. Faulty Blend Door Actuator

The blend door actuator is used to regulate hot versus cold air. If you turn on the AC but only get hot air, this actuator might be the problem.

8. Damaged Compressor Clutch

The compressor in most cars uses a clutch to power the system. If the clutch is damaged or too old, it could stop working. Electric and hybrid vehicles may not use a clutch, but they can blow fuses, necessitating a replacement.


How to Check Your Car AC

If your AC has stopped working in the car, there are a few things you can check and troubleshoot on your own. 

  1. Check to see if the cabin filter is clear; if not, replace it.
  2. Figure out the last time the condenser was replaced. Normally, you need a new one every 10 years.
  3. When the AC is on, listen to hear the condenser hum as it spins. If you hear loud banging or scraping noises, that’s a sign something is broken.
  4. Make sure the condenser is free from leaves, bugs, or other debris.
  5. Check for leaks in the system. You can get a UV leak detection kit from the local auto parts store and follow the instructions.
  6. Tighten all connections on the AC system to see if a loose connection is the problem.


How to Fix Your Car’s AC 

In some cases, you may be able to purchase a new part and install it yourself. You can often purchase repair kits from local auto parts stores and watch instructional videos teaching you how to fix the system.

These repairs often require specialized tools and equipment. If you’re not confident you can handle the issue, we recommend turning to the experts. A professional will have an easier time repairing your car and getting it running again quickly.


How to Prevent Common AC Problems

The best way to take care of your AC system is to perform regular maintenance so it’s less likely to break when you need it most.

  • Months of sitting dormant during the winter can damage the system. Even in the cold months, run the AC system once a week on its highest setting for a few minutes to ensure it’s working correctly.
  • Every couple of years, you should get the refrigerant charged. You can buy kits to do it yourself, but you can also take the car into a shop to have professionals do it.
  • Look at the car’s user manual to determine how often you should change the filter. Make sure you change it every time it’s due.
  • Wash the car regularly, and rinse off under the hood so the condenser stays free of debris buildup.


Visit CARSTAR For Your Car Repair

When your AC system isn’t working right, and you want a quick repair, it’s time to call CARSTAR. CARSTAR specializes in quick, quality repairs that get you back on the road driving comfortably in no time. Our experienced technicians know all the ins and outs of AC systems and can easily find and fix the issue. 

To get your AC system running again or for any other repairs schedule an appointment at a Carstar location near you. Don’t hesitate to reach out if there’s anything else we can do.