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How to Check if Car AC Is Working Properly?

Air conditioning can be an absolute lifesaver, especially if you live in a warm climate. 

Thus, you want to ensure everything works properly before the hot season begins. 

The easiest way to make sure your car’s AC is working properly is to ensure your vents blow out cold air. Or, if you want a closer look at your AC, open the hood and make sure you don’t hear any odd sounds and that everything is running as it should. 

In this article, I will detail the four methods you can take to check if your car’s AC is working correctly. 

Then, I will discuss what temperature your AC should blow at, what to do if your AC doesn’t blow at all, and how much it costs to get your AC fixed. 

4 Methods to Check if Car AC Is Working Properly 

A woman's hand checking the car's air conditioner.

If you want to make certain your car is ready for the warmer months, you need to follow these methods to ensure everything is up to par. 

Method One: Check That Your Vents Blow Cold Air 

The easiest way to check to ensure your AC is working is to see if your vents are blowing out cold air. 

To perform this test, all you need to do is start your car and turn on your AC to the coldest setting. 

Then, place the back of your hand up to the vent. 

Is it blowing out cold air?

Or, is the air only slightly cool, room temperature, or even hot?

If the air is not actually cold, your AC is not working as it should. 

Method Two: Check That the Compressor Clutch Engages

In order for your air conditioner to work properly, you need the compressor clutch to engage. 

Thus, if you want to check the health of your car’s AC system, you should ensure the compressor clutch is working how it should. 

To tell if the clutch is engaging, you first need to locate it. 

So, open your hood and look for the AC compressor

You will find the AC compressor in front of the engine. 

This piece will look like a metal cylinder with a moving belt on one end. 

The compressor clutch will be on the outside of the belt and looks like a black drum. 

Once you’ve located the compressor clutch, you can turn the car on. 

But, before you do so, you should secure any loose clothing, dangling jewelry, or long hair so that none of these things get caught in the car’s moving parts. 

Next, turn your AC to the maximum setting before returning to the front of your vehicle. 

Now, watch the compressor clutch and see if it engages. 

If it is engaging, the clutch will spin. 

If it does, your compressor clutch is engaging. 

Just remember, though, that the compressor clutch will not spin continuously. 

Rather, it will go through cycles of spinning and being still. 

Yet, if your clutch does not move at all, it is not engaging, and you will need to get it fixed. 

Also, while you’re paying attention to the compressor clutch, you should check to see if you hear it making a clicking or rumbling noise. 

If it is, you should have it checked by a mechanic. 

Method Three: Check Your AC Belts 

For this step, you need to get under the hood again. 

After opening the hood, inspect all the belts on your AC unit while the car is off. 

Look for cracks and excessive wear. 

If you notice damage on any of your AC belts, your AC may stop working soon. 

Next, turn your AC on and recheck the belts. 

If any of the belts are vibrating, this may indicate a loose belt that you will need to have tightened. 

Method Four: Check Your AC Hoses 

Now, you need to inspect your AC hoses for signs of wear and tear, such as cracks and leakage. 

You should also look for dirt, leaves, or any other debris around your AC hoses or other parts of your AC system. 

Any of these issues could lead to problems with your car’s AC. 

If you notice any cracks or leaks in your AC hoses, you should take your car to a mechanic to have the problem addressed. 

When it comes to debris, you can simply clean it off with a garden hose. 

But, when you do this, make sure not to spray too vigorously, or you could damage the inner workings of your car. 

Also, never stick your hands down into your hood if you are not a trained mechanic because even if the car is off, certain fans can come on and harm you. 

How to Differentiate Between Cool and Cold AC Air

As I stated above, the easiest way to test if your air conditioner is working is to ensure the vents are blowing out cold air. 

But what exactly is “cold?”

And how can you differentiate between cold and cool?

Well, if your air conditioner is indeed blowing out cold air, the air should be 45°F (7°C) or below. 

If you want to be certain your AC is blowing at an adequate temperature, you need to get a proper reading with a thermometer. 

To do this, you must park your car in the shade with the windows rolled up and then leave your air conditioner running on the maximum setting for ten to twenty minutes. 

Then, choose one of the air vents and make sure you have it completely opened. 

Next, stick the thermometer up to the vent and wait for the thermometer’s temperature to settle. 

It should read at 45°F or below. 

If not, your AC may not be working correctly, and you need to get it serviced. 

What if No Air Comes Out of My Car’s AC Vents?

A woman wearing a blue and white striped blouse is feeling hot inside the car while checking the car's air conditioner.

Although it’s more common for a faulty car AC to expel warm or room temperature air, it sometimes will blow out no air at all. 

Most commonly, this issue occurs when your AC fan stops working. 

Usually, to fix this problem, you just need to check your blow motor resistor and blow motor module. 

In most cases, one of these will not be working, and you need to replace it. 

Alternatively, your cabin air filter may be clogged. 

You see, the cabin air filter cleans contaminants out of the air that comes into your AC system from the outside environment. 

Thus, this filter can get clogged with debris, making it not work as it should. 

If this is the problem with your AC, you need to get a new air filter. 

How Much Does it Cost to Repair Car AC?

Since there are so many different reasons a car’s AC can fail, the price of a fix can vary dramatically. 

At the lowest end of the spectrum, you’ll only need to pay about $20 to $50 to get your refrigerant recharged or your cabin air filter replaced. 

However, extensive AC repairs can cost several thousand dollars. 

In general, most people will pay between $100 and $900 to get their AC fixed. 


The easiest way to check that your AC is working how it should is to make sure the vents are blowing cold air. 

Or, if you want a closer look at your AC, you need to get under the hood to inspect certain AC components, such as the hoses and compressor clutch.

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