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Why Is My Car Air Conditioner Hissing?

Auto Parts and Accessories · November 3, 2022

Usually, the hissing sound comes out of your car’s air conditioner for three reasons, such as- refrigerant leaks, internal valve leaks, and air compressor malfunction. If you encounter such problems, the first thing you have to do is to troubleshoot to find out the leak or the source of the problem. 

But sometimes, the hissing sounds are quite temporary. So before you ask for any expert’s assistance, look for other signs that indicate any kind of leakage. To know more about why is my car air conditioner hissing, keep digging further.

Why Is My Car Air Conditioner Hissing

Why Is My Car Air Conditioner Hissing

You cannot expect the air conditioner of your car to be completely silent. But you will know the difference between any normal sound and a sound that means trouble. Especially, if the sound is coming from your air conditioner, you will have to be extra careful.

However, air conditioning does not always remain silent. From time to time, you might hear some sort of unexpected sounds while you are driving your car. But the thing that should concern you is why your car is making that sound. Now that can be any minor issue or just a reminder that your air conditioner is getting older.

But there are some types of noises, that you should take seriously. And the most common noise that might come from your car’s air conditioner is the Hissing sound. 

If the hissing sound lasts only for a few seconds, you do not have to worry about it. Sometimes the refrigerant gas in the expansion valve makes this hissing noise. In that case, you can leave the air conditioner as it is.

But when you notice that a hissing sound is coming out continuously from the air conditioner, that can be a sign of a leak in your expansion valve or the refrigerant. Usually, the leak takes place in the internal valve or the expansion valve. 

So let’s talk about that and the other common reasons that cause this hissing sound.

Refrigerant Leaks

Refrigerant Leaks

Refrigerant leaks are considered to be a major issue for your air conditioner. And if you do not take care of these leaks from time to time, the leak can expand and make the case even worse. 

Besides, it can cause damage to the air compressor that can lead to a disaster for your air conditioner. So until you fix the issue, keep the air conditioner turned off. Apart from the reason that the leak might expand, the gas coming out from the leak can cause serious damage to your health as well.

In this case, the first thing you should do is troubleshoot to find out the problem and then take action immediately. Hiring an air conditioner technician to repair or replace the refrigerant would be a great idea. And make sure that they follow the process mentioned down below

Step 1: Troubleshoot and locate the leak.

Step 2: If the refrigerant leaks, repair it. If that cannot be done, replace it with a new one.

Step 3: Once the repairing or replacing is done perfectly, refill your air conditioner with refrigerant.

However, to make it easier for you, here are some signs that your refrigerant has leaked:

  • It takes more time to cool off the cars indoors than usual. Because the refrigerant is not absorbing the heat from the car as it should. 
  • When the supply vent blows warm air, it means there is a leak in your refrigerant. 
  • When there is a leak in the refrigerant, it takes more time to absorb the heat. As a result, the power consumption becomes higher than usual. 

Leak in the internal valve

Leak in the internal valve

If there is no leak in the refrigerant, there might be a leak in the internal compression valve. This is the valve that takes the internal air pressure of the compressor to equilibrium. 

To tackle the situation, you will have to repair the valve immediately. Otherwise, the case might get even worse.

Air compressor malfunction

Sometimes, the air compressor is subjected to high air pressure internally. In that case, when the internal air pressure is too high, the air compressor becomes a little vulnerable. And if the pressure remains constantly high inside the air compressor, it might cause the air compressor to malfunction.

However, the air compressor is the most expensive part of the air conditioner, both the home air conditioner and the air conditioner in your car. Whether you want to repair or replace the air compressor, it will cost you a lot.

As a result, most people prefer to replace the whole air conditioner unit instead of just repairing or replacing the air compressor. Because replacing the whole air conditioner is more reasonable than the other options. And considering the durability, this might be a more cost-effective decision as well.

How to fix the Hissing noise coming out from the car’s air conditioner

How to fix the Hissing noise coming out from the car’s air conditioner

As we have mentioned earlier, it is not necessarily a bad thing that your car’s air conditioner is making a hissing sound. But if that noise is occurring non-stop, it is a must for you to take action. 

But before you go any further with the technician, you can try the following suggestions to fix the hissing noise.

AC Superseal

To fix the refrigerant leakage issue on your car’s air conditioner, AC super seal is considered to be one of the most popular DIY solutions. Besides, the price of the super seal is pretty reasonable.

When you will apply the super seal to the refrigerant leakage, it will go as liquid as it first. But when the super seal is exposed to normal temperature, it will harden itself on the leakage and seal the leak. Thus the refrigerant will be able to flow smoothly.

Replacing the faulty valve

This is a rather more economical option. If you detect issues in the internal Schrader valve, you can just replace it with a new one on your own. And this might be the only valve that can be removed and re-attached without any expert’s assistance. 

To determine, if the issue is with the Schrader valve or not, you can just remove the valve by screwing it off. And then check for excess oil or refrigerant/freon bubbles. If you find any of these, just replace the Schrader valve.

Frequently Asked Questions

Why does my car AC hiss when I turn it off?

The hissing sound does not mean trouble all the time. And if your AC makes a hissing noise even when it is turned off, it might be just equalizing the internal pressure. 

How much does it cost to fix the refrigerant leak in the car?

Depending on the condition of the leak, it can vary from 100$ to 800$. Mostly, the hose gets cracked and hence causes the leak. If that is the case for you, replacing just the cracked hose can fix the issue for you. And if other parts like the condenser or the compressor need to be replaced, it will cost you a fortune. 

Conclusion

You do not have to worry about the hissing noise coming out of your car’s air conditioner every time you encounter them. But if the other signs look suspicious to you, troubleshoot to find out any leakage or fault in the system. And now that you know, why is my car air conditioner hissing, you can face the problem more professionally.

Filed Under: Auto Parts and Accessories

Mihailo Savic

First and foremost, I am a mechanical engineer. I graduated from the University of Waterloo in 2018 with a degree in Mechanical Engineering.
I have also gained experience in various industries such as aerospace, construction, oil & gas, etc, through my work with different companies.
Also working in the field of pressure equipment (vessels, pipelines and steam generators), such as inspection and testing.

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