7 Reasons Why Car AC Is Not Blowing Cold Air

Nothing feels as good as turning on your car’s AC on a hot day and having a blast of cold air rushing over your skin. Warm air, however, is annoying, which brings us to today’s topic; reasons why car AC is not blowing cold air.

There are many reasons for this problem, but the most common ones include a refrigerant leak, an AC compressor that’s not engaging, electrical issues, and many other issues. Before you rush to the nearest dealership, let’s understand these problems because some are easy to fix at home.

Reasons Why Car AC Is Not Blowing Cold Air

Here are the most frequent culprits why my car AC is not cooling.

1.   Refrigerant Leak

Refrigerant is the fluid responsible for your car’s cooling. It’s recycled over and over as it expands and contracts when removing heat and humidity from the cabin. In a properly functioning vehicle, the refrigerant remains at the same level. A low refrigerant level indicates a leak in the system, often followed by warm air blowing from the AC.

You can recharge your car’s refrigerant at home. However, the leak needs to be fixed first, which is not as easy as it sounds. This is because refrigerant evaporates once it contacts air. Thus, it’s best to have a professional mechanic check the vehicle.

In any case, it’s good to know some of the signs that indicate you have a refrigerant leak. These are:

Once a leak is found, a mechanic can repair the AC refrigerant leak car or replace any failing components. Then, you can go ahead and recharge the coolant at home.

However, if your AC system needs flushing, it’s something you cannot do at home. This process requires a certified professional since the refrigerant needs to be captured as it is harmful to humans and the environment. For this reason, it’s important to wear gloves when handling refrigerant.

2.   AC Compressor Is Not Engaging

The AC compressor is a critical part of the vehicle’s HVAC system. It circulates the refrigerant around by allowing it to suck up hot air. The AC compressor cools the refrigerant and recirculates it for further cooling.

When the AC compressor malfunctions, it shows signs such as car shakes when AC is on, growling noises, and diminished airflow.

A critical part of the AC that makes the cooling process possible is known as the shaft. This is the component that rotates when the AC is on. The shaft pushes against a clutch to kickstart the cooling process. When the clutch refuses to engage, the shaft will rotate freely without any cooling.

Fortunately, troubleshooting this issue is straightforward. Turn the AC to the “heat mode.” Then, pop the hood and locate the compressor. You’ll see a disk on the pulley side of the compressor. This is the clutch, and it should not be moving when running the “heat” setting. Now, go back to the car, switch to “cool” mode, and check if the clutch is moving. If it’s disengaged, it’s not working correctly and needs to be replaced.

3.   AC Accumulator/ Drier Is Not Working Properly

The accumulator/drier filters particles and moisture from the vehicle’s AC. It also stores the refrigerant temporarily. When the AC accumulator is not working properly, it may lead to problems with the other parts of the AC.

The signs of drier failure include valve-based refrigerant leakage, abnormal noise, ineffective cooling, bad smells, and cloudy sight glass. Unfortunately, you can’t change the AC drier on its own owing to warranty regulations. So, you will find that the compressor also needs changing. The evaporator and condenser will also need to be replaced in severe cases.

4.   Bad AC Condenser

The AC condenser is similar to the radiator and works in sync with the radiator fans. Its main job is to cool the refrigerant and change it from gas (hot) to liquid (cold). Nonetheless, the condenser ages with time, leading to wear and tear of the tubes and seals. Unfortunately, you cannot repair these parts, and the entire AC condenser will need to be changed.

Another common problem that may cause a bad AC condenser is debris in the tubes, causing a blockage. These contaminant particles damage the AC’s components as they flow in the tubes. Often, these are metallic particles that come from a broken AC compressor. As a result, it leads to the AC not blowing cool air. Thus, the entire AC condenser and compressor may need replacement.

5.   Electrical Issues

Your car’s air conditioner could be blowing warm air because of problems with the electric modules. First, a wire could be frayed, or there could be a blown fuse. Diagnosing this problem starts with a visual inspection of the car’s fuse box and wiring. If any wire is frayed, it needs changing since it could cause hot air to blow from AC.

Next, test the fuses using a 12V voltmeter to see if all of them are outputting 12 volts. If one of them is blown, just change it, and the AC will resume working properly.

6.   Blend Door Actuator Gets Stuck

The blend door actuator is the part that switches the temperature from hot to cold and vice versa. After switching on the AC, the blend door swings over the ventilation system and blocks any warm air from entering the cabin.

SYMPTOMS OF BAD BLEND DOOR ACTUATOR

When the blend door is stuck or completely broken, your AC will give you air at the wrong temperature. In our case, hot air when you want cold air. You can repair or change the blend door at home. However, it’s located in the middle of other components behind the dash. So, if you don’t know what you’re looking for, it’s best to leave this job to a professional mechanic.  

7.   Problem with Fans

When the fans switch from cold to hot air, you may ask, “why is my air conditioner not cold anymore?” The culprit here is a broken fan motor that sits at the front of the car’s motor. You’re likely to hear noises behind the vent or whirring noises that get louder when the fan speed increases.

A mechanic should diagnose a broken blower motor. In any case, they will recommend repairs or changing the blower motor.

Conclusion

These reasons why car AC is not blowing cold air are the telltale signs of AC failure. Please have them checked by a professional to prevent further damage to your vehicle’s air conditioning system. Don’t let hot air ruin your drive when you can have cold air running in a cinch.


I’m Tim Miller, an automotive mechanic, and blogger from Denver, Colorado.

Biography

I’m the Editor In Chief of gmundcars.com and angf35eis.com.

My fan page is facebook.com/autozikcom.

I’ve had over 15 years’ experience in car repair and using OBD scanners.

My reviews and articles about car repair and maintenance can be found on my own websites.

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