why does my car ac smell like vinegar header photo

Why does my car AC smell like vinegar?

If you’re thinking to yourself, why does my car AC smell like vinegar, you’ve come to the right place. In this article, you’ll learn why your AC smells like vinegar and what you can do to make it go away.

So why does my car AC smell like vinegar anyway?

The most common reason why this happens is because you have funky shit growing in your air conditioner system.

This nastiness growing in your car AC can take on different scents. If vinegar is what you are smelling, you might want to consider yourself lucky. Sometimes a car AC can smell like a musty basement, dirt, or even smelly socks.

 So why is this happening?

The answer is simple: moisture.

Where does the moisture come from?

You’re not reading this to learn how a car AC system works. But it’s helpful to know where the moisture is coming from. Let me explain without going too far into the technical details.

Water, condensation, moisture – whatever you want to call it – is a byproduct of your car’s AC system. 


Did you ever notice the puddle of water under your car on a hot day when you run the air conditioner? This water is a byproduct of your car’s air conditioning system.


The same thing happens with home air conditioners. Have you ever noticed an AC window unit dripping water on a hot summer day? 

It’s the same thing that happens in your car. All cars’ air conditioners will drip water. It isn’t a problem unique to your car. 

And to be clear, it’s not a problem at all – condensation is part of the air conditioning process.

photo of a sweating glass of water

One of the parts of your car’s air conditioning system is called the evaporator. The evaporator is basically a  part of the system that gets very cold. It cools the air that is then forced through the air ducts in your car.

Because the evaporator gets very cold and the air is hot, the evaporator sweats. 

It’s a lot like what happens to a glass of ice water on a hot day. The glass starts to sweat and ruins the wood table it’s sitting on (sorry, mom… I’ll use a coaster next time).

This water is collected and is drained out the bottom of your car through a drainage hose.

So…. long story short…. Given all the water that is created by your evaporator, it can be a place where mold and mildew will grow. Plus it’s dark inside of your AC system so sunlight isn’t helping to dry it out.

Other places where mold and mildew grow

Your evaporator isn’t the only place that can grow nasty, smelly stuff. You can also grow it inside of your air ducts.

Think about how hot your car can get on a sunny summer day. Everything inside of your car is scorching hot – including your air ducts. 


So when you turn on your car AC and rush ice cold air through those ducts, condensation can form just like it does on your evaporator. 

Plain water in your car’s air ducts generally won’t smell.

Here’s the problem… over time, other things end up in your air conditioner ducts. There could be dust, pieces of dried leaves, or even dead bugs (hopefully you don’t have roaches in car!).

These things accumulate and can hold water a little longer and start to make a funky mess that smells like vinegar (or worse).

And when this gross gunk is in your vents, you’re basically blasting vinegar-scented air into your car. Which, by the way, isn’t healthy for you or your passengers to be breathing in.

Awesome.

How do I get the vinegar scent out of my air conditioner?

Now that you know the answer to the question why does my car AC smell like vinegar, you’re probably wondering how the Hell do you get it out?

First I’ll tell you what won’t work – those stupid air fresheners that attach to your air vents. 

All they will do is mask the problem. Poorly.

The air will now smell like vinegar AND pumpkin spice. Yay!

Know what else won’t work? Spraying air freshener into your vents. 

Just don’t. 

What you need to do is get to the source of the problem. And doing this is easier than you might think. All you need is a can of Lysol and a little know-how.

How to use Lysol to get rid of the vinegar smell

On most car AC systems, you have the option to use either fresh air from the outside or recirculated air inside of the car. 

In this cleaning procedure, you’re going to want to use fresh air from the outside.

What you’re basically going to do is spray Lysol into the fresh air intake while the system is running. This will suck Lysol into your vents and blow it out into the car cabin. Along its journey, the Lysol will coat the insides of your air ducts and attack the mold and mildew.

Step 1: Find your car’s fresh air intake

For most cars, you can find it at the base of your windshield. On my Audi allroad, it’s covered by a plastic shield. I had to remove the shield to access the intake.

If you’re having a hard time finding the fresh air intake on your car, check out your owner’s manual or search it up on Google.

A way to be sure you’ve found your air intake is to run your AC  on high (and in fresh air mode) and put your hand over the vent. You should feel it sucking air in.

Step 2: Remove your car’s cabin air filter

Many cars use filters to clean the air coming through your car’s vents. You’ll need to remove it in order to clean your air ducts effectively. If you leave the filter in place, it can basically block the Lysol and keep it from working.

Cabin air filters are typically located under the dashboard of your car.

They can also be located at the base of the windshield in the same area where the air intake is. If you don’t know where your cabin air filter is, reference your car’s owner’s manual and it will tell you where to find it.

While you have the filter out, you might as well replace it. If you haven’t replaced it lately (or at all!) your dirty filter may be contributing to the reason why your AC smells like vinegar!

Step 3: Turn on your AC and fan

This is pretty self-explanatory. Just turn on your car and switch on your AC to the high setting.

**IMPORTANT** Make sure you have it in fresh air mode and NOT recirculating air mode. This cleaning strategy won’t work if you are in recirculation mode.

Step 4: Roll down all the windows in your car

Since you’ll basically be blasting Lysol through your car’s vents, you’ll want to air it out. 

Yes, Lysol is attacking the mold and kills germs, but it’s still a chemical and it’s not something you should be breathing in. 


The good news is that it dissipates fairly quickly.

Step 5: Spray Lysol into your intake vents

Depending on your car, there may be more than one intake vent under the hood. Give each vent a good blast of Lysol (10 seconds, give or take) and let your AC run for a few minutes.

Put your (new) cabin filter back in and you should be good to go!

In most cases, this should solve the problem of your car AC smelling like vinegar.

photo of lysol in AC air intake

Why does my car AC smell like vinegar STILL?

If you try the above process, and you’re still asking yourself why does my car AC smell like vinegar, don’t give up yet! 

photo of a dirty ac evaporator
Dirty evaporator
photo courtesy of e90post.com

What’s most likely happening is that your car AC evaporator has a ton of smelly funk growing on it. There’s lots of tiny fins on your evaporator and if the funky stuff starts growing out of control, it can get really bad.

How do I clean my car’s AC evaporator?

A good car AC evaporator cleaner is Klima Clean. It’s a foam that expands and sticks to your evaporator. And as it melts away and turns to liquid, it takes away all the funky crap with it

Cleaning your car AC evaporator is going to take a little more work because accessing it can be difficult. Your car AC evaporator is typically behind your dashboard.

Your car owner’s manual may show you how to access it.

If your owner’s manual doesn’t tell you where your evaporator is, try a Google search.

Ideally, you’re going to want to spray the Klima Clean right on to your evaporator. It works like this:

What if my evaporator is difficult to access?

Depending on your car, accessing your evaporator may be very difficult. You may have to take off your entire dashboard to access it. Take it from me, this isn’t an easy job!

But don’t worry, there’s another way to access your evaporator – through the evaporator drain tube.

A can of Klima Clean will come with a long tube that will fit inside of your car’s evaporator drainage tube. Just slide it in (that’s what she said!) as far as it goes, and depress the button. 

This will send foam up into the bottom of your evaporator drain. It will expand and cover the evaporator.

Remove the tube, let the foam do its work. It will drain out as liquid.

Where is my car evaporator drainage tube?

Finding this is easier than you think. Just let your AC run for a while on a hot day and wait for it to start dripping condensation. 

You can then get under your car and look for the tube where it’s coming from.

Can I spray Klima Clean in through the vents?

If your evaporator is too difficult to access AND you can’t access your drainage tube, can you just spray Klima Clean into your vents?

I’m not going to say you can. In fact, if you read the Klima Clean packaging, it says you should not do this.

However, there are several people out there on YouTube who do it and say it works. 


I’m not recommending you try this. But if you want to believe a random guy on YouTube….

How do I prevent my car AC from smelling like vinegar?

Now that you know the answer to why does my car AC smell like vinegar AND you know how to make it go away… how do you prevent the vinegar smell from coming back?

Dry out your vents

When you use the air conditioner in your car, the air is inherently moisture rich… so it tends to create a damp environment in your car AC ducts. 


As you learned earlier, this damp, dark environment fosters growth of the nasty stuff.

A way to help dry out your ducts is to run your car’s fan on high for a few minutes WITHOUT the AC being on.

You can just let the car sit for a couple minutes after you arrive at your destination.

Or, when you know you’re a couple minutes away from your destination, just click off the AC and run the fan only just before you arrive.

Doing this will force dry air through the system and it will help evaporate any moisture that has accumulated in your ducts.

Try not to use the recirculated air setting

If the air coming out of your car AC vents smells like vinegar, using the recirculate setting can actually compound it.


Think about it… you’re taking a smelly air source and feeding it with more smelly air. Duh.

Also, recirculated air tends to be more humid, and therefore fosters the moisture within the system.

To illustrate, have you ever tried to defog your windshield with the recirculated air setting? It doesn’t work well because you’re trying to combat moisture with humid air. Damp + damp = damp.

What about other car AC freshening products?

You’ll find several car AC duct cleaning products at your local auto parts store that do the same thing as Lysol. I’m just suggesting you try Lysol because there’s a good chance you have a can of it in your house right now. I’m all about saving time and money!

What about fogger products?

To use these products, you roll up all the windows, blast your car AC on recirculation mode, set off the fogger, and close the door. 


The idea here is that the chemical fills the inside of your car’s cabin and the chemical-rich air is continually recirculated through your AC vents.

This does the same thing as spraying Lysol into your air intake. 

Personally, I don’t love the idea of it. I’d rather not have the chemical all over the inside of my car. With the Lysol trick, it’s just in your ducts and it should dissipate quickly when it exits the vents because your windows are open.

Conclusion

The answer to why does my car AC smell like vinegar is simple: Moisture and mold growth. The good news is that you can most likely make it go away with a can of Lysol. But you have to use it the correct way. Spraying it directly into your vents won’t work. You need to spray the Lysol into your car’s AC air intake so that it flows through the entire system. If that doesn’t work, you may need a deep clean of your car’s AC evaporator which you can also do yourself fairly easily.

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