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car ac turns on and off randomly

8 Reasons Why Your Car AC Turns On And Off Randomly

Driving around on hot summer days isn’t any hard because the air conditioner in your car can fight the heat. But what if your car AC turns on and off randomly?

Multiple reasons will cause the AC to malfunction. You need to find the reason first and then find the best solution. 

This article will explain why your car AC experiences this issue. Let’s read on and learn how to fix it properly! 

Car AC Turns On And Off Randomly

8 Reasons Why Your Car AC Turns On And Off Randomly

The car’s AC system transfers the refrigerant from the liquid form to the gaseous form through temperature fluctuations and the programmed pressure. It then draws heat and moisture within the car and releases cold, dry air in return. That’s how the car AC works. 

The air conditioning system involves multiple components. Hence, any fault within the system will cease the whole process. 

After understanding how the AC works, you can answer the question, “Why does my air conditioner turn off by it self?” easier. In fact, there are several causes for this problem. And we will discuss each right now. 

Short Cycling

The most apparent phenomenon that causes the car AC to turn on and off is brief cycling repeatedly. 

The AC compressor runs continuously until your car compartment hits the thermostat-set temperature. One cycle may last 15 to 20 minutes before the compressor turns off. Then, it restarts the cycle once the temperature in the car goes up. 

When the compressor stops too soon, the cooling cycle will get shorter. Primary reasons for the short cycling include the following: 

  • Clogged air filter
  • Wrong sized AC
  • Refrigerant leaks
  • Faulty thermostat 

Dirty Air Filter

The air filter is the most common reason for AC issues. For example, dirt will build up if you forget to clean or replace the old filter. Then, the clogged filter will cause your AC to go in and out randomly. 

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The dirt buildup also limits the airflow into your AC, freezing the coils. As a result, the AC turns off suddenly while not completing a full cooling cycle. 

This problem is easy to solve as it just requires you to clean the air filter. If it’s too old, you may need to replace it with a new one. 

Refrigerant Leak

In a car AC, freon acts as a non-flammable gas. It takes part in the process of evaporation. So, refrigerant leaks or low freon levels lead to the AC’s continuous on/off operation.

The sign of the leak is the thin, oily substance developing in the cabin, under the hood, and around the compressor. You will also notice a hissing sound from the system. Of course, it won’t be as loud as a lawn mower , but you still feel annoyed. 

You must find the leaks and apply the leak sealers in this case. If your AC still leaks, ask for professional help. 

Compressor Failure

The compressor builds pressure and transfers freon constantly to keep the AC working. If it malfunctions, the system won’t have enough cooling power. In the end, your car AC turns on by itself and then turns off suddenly.  

The leading cause of the damaged compressor is leaving it inactive for too long. Components in the compressor tend to clump together and can’t function well as a result.  

To prevent this problem, remember to turn on the AC frequently. Even if you don’t intend to use it, run it for about 15 minutes every other week to keep its components in good condition. 

Meanwhile, once the AC compressor keeps turning on and off, you need to replace the compressor. 

Unfortunately, if the metal chip is the cause of the defective compressor, you may need to replace the entire AC. 

Blown Fuse

If you find that your AC only operates when the engine is on, one of the car’s circuits may have a blown fuse. This issue may stop other components of your automobile from functioning properly. 

But how to tell if your fuse is blown? In most cases, you’ll need to check your owner’s handbook to determine which fuse is in charge of the AC. But if you can’t, you must contact a professional for help. 

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Then, by lifting the cover, you may examine the fuses in your automobile under the hood. It will be simple to identify a blown fuse since the blackened metal may be on its wire. 

Another method to determine whether the AC fuse has blown is to measure the voltage across the fuses. 

Damaged Blower Motor

Defective cooling fans are another common cause of inconsistent cooling. Because of the restricted airflow, the blowers must work even harder to cool the vehicle’s compartment. 

In this case, the malfunctioning blower motor can only generate hot air, causing the AC to overheat. Eventually, the car AC blower turns on and off repeatedly. Another sign of the faulty blower motor is the strange sound. 

Why do the blower motors break down? It may be due to electrical issues, including electrical connections or blown fuses. 

Bad Condenser

The condenser is in charge of collecting heat within the engine and transferring it into the air outside. So if this part doesn’t perform well, your AC will start to shut on and off. 

Defective Blend Door Actuator

The blend door actuator controls the automobile’s temperature control system. It works by receiving signals sent when you adjust the airflow temperature. 

If you have checked other components in the AC and found no issue, the problem may come from the malfunctioning blend door actuator. 

A faulty blend door actuator can suddenly make your AC turn on and off. The signs for this issue are:

  • Clicking sound from the HVAC control on the dashboard. 
  • Strange noise whenever you adjust the AC’s temperature. 
  • Sudden temperature fluctuation between cold and hot while you don’t even modify it. 

How Often To Recharge The Car AC

How Often To Recharge The Car AC?

AC recharge refers to the process of adding refrigerants to your car. Before the recharge, the mechanic will test for any leaks or problems in the AC. 

In fact, the refrigerant in your car AC will never run out. Hence, if you don’t notice any signs of damage or leakage, AC recharge will be unnecessary.

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The best indicator that the AC needs a recharge is when the AC system starts to cool at a slower speed, and its performance decreases significantly. 

How Much Does It Cost To Repair A Car AC?

The cost of fixing a car AC depends on multiple factors, such as its severity and warranty policy. Sometimes, you can repair it yourself, which significantly cuts the cost. 

If you ask a mechanic to fix the problem for you, he may cost you about $2,500. This fee also involves checkup and upkeep costs. 

It may seem like a lot. However, please note that you may want to fix the AC by yourself in most cases. And only when the problem is severe will you take it to the repair store. As a result, the average cost we mentioned above is for significant damage. 

Can You Drive With A Broken AC?

No. It’s not a good idea to drive with your broken AC. Even if you seem fine when getting too hot in your car, the system won’t feel the same way. 

First, please note that all the components in your car are connected. So every problem with a small part will damage the other. 

To be more specific, the AC compressor has pulleys and belts operated by the engine. Hence, when they break down, the engine will overwork to power them. Finally, your car’s overall safety and efficacy will decrease. 

The more time you spend driving with a damaged AC compressor, the more harm you potentially cause to your vehicle engine. The overall air conditioning system will suffer, too. 

Instead of driving your vehicle, it is more cost-effective and safe to have it repaired by ASE-certified auto AC experts. 


There are multiple reasons why car AC turns on and off randomly. You need to check several components within the system. Only after you find out the cause can you solve it. 

It would be best to check the AC regularly to avoid dirt buildup. AC recharges will also help prevent this problem. 

Hopefully, you will find this guide helpful. Thank you for reading, and see you in the next post! 


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