Home AppliancesAir Conditioner

What Happens If You Put the AC Filter In Backward?

A Guy Adjusting The Ac Filter

If you’ve noticed that your AC filter is clogged, even though you just installed a new one, you may have put the filter in the wrong way around.

When an air conditioner’s filter is facing the wrong direction, the end of the device that usually collects debris from the air in your home isn’t able to do its job properly. This leads to a clogged filter and uncleaned air.

It may also result in higher utility bills as the AC struggles to complete its task.


There are a few things that may happen if you have a backward AC filter; these include:

  • Decreased air quality: When your AC cannot correctly filter the air in your home or other space because the filter isn’t the right way around, you can expect your air quality to be poorer than it usually is.
  • Higher energy usage: When the filter is installed backward, the AC will still try to push air through it, but the machine will have to work much harder to do so.
  • Health issues: For homeowners that have health issues affected by poor air quality (such as asthma), you may experience difficulties when your filter is not operating properly.

In more severe cases, after an AC has been functioning with a reversed filter for some time, the clogged filter can cause irreparable damage to the AC unit.

If you’re concerned that you may have installed your AC filter backward, you’re in the right place.

In this guide, we’ll help you understand how to install your AC filter the right way around, why it’s important to install the filter correctly, and what can happen over time if you don’t.

Ways To Avoid Installing Your Filter Backward

Technician Repair Air Conditioner In Customer Home

Surely, if you can avoid the problem altogether, that’s going to be better for everyone. Installing a new filter for your AC doesn’t need to be an anxiety-inducing chore.

1. Have a Professional Install Your New Filter

By hiring a professional to come and install your new AC filter for you, you suddenly gain the chance to watch an experienced person install part of your AC.

Watch closely, and you should be able to pick up the ins and outs of installing that specific type of filter.

Check Reviews Before Hire

There are two crucial things you must do before hiring anyone to come and help you with your AC:

  • Check their reviews and references online.
  • Don’t pay in advance.

Only pay when the job is done, especially for a small job like an AC filter replacement. This kind of work shouldn’t cost much at all, so if you think you’re being quoted too high of a price, shop around and get more quotes from other contractors.

2. Check Your Filter for Helpful Features

Some AC filters will have small arrows marked on them as an installation guide. Not all filters will have these, or they may not be very noticeable, but it’s worth checking your filters for them.

These arrows point in the direction that air flows through your AC, so you should install the filters facing away from the supply ducts, as indicated.

3. Check Out Some How-To Videos

YouTube is an excellent place to look for instructional videos these days. All kinds of videos get uploaded, including instructional videos for homeowners.

It’s worth a shot if you’re not quite at that.

How to Find a Good How-To Video

Unfortunately, you won’t be able to just click on any AC filter replacement video to get the answer you need. Look for:

  • A title that lists your model of AC.
  • A YouTube channel with other instructional repair videos.
  • Clear instructions.

You can usually tell when it’s an amateur filming a how-to, and though that’s not always a bad thing, you want more professional advice when messing around with your AC unit.

What Happens When You Install Your AC Filter Backward?

Ac Filter Installed Backward

In the event that you do install your AC filter backward, it’s unlikely that you’ll notice at first. A filter that’s the wrong way around shouldn’t make noticeably strange noises, and it won’t tip you off that there’s an issue straight away.

As such, here are some warning signs:

1. Your Filter May Seem To Be Struggling

You might hear some weird noises or notice that your AC unit is getting warmer than it used to. It’s not unusual for an AC to overheat when there’s an internal issue.

2. Your Utility Bill May Start Rising

No one notices this right away because many other machines in your home are using energy. It’s also hard to see changes in a utility bill during certain times of year (like in the transition from warmer to colder months).

An Air Conditioning unit that is struggling because its filter is the wrong way will use a little more power as it pushes through its internal blockage. If it’s left like this for some time, the rise in your bill should become more evident.

3. Your Health May Deteriorate

Homeowners or renters with AC units that rely on cleaner air for their health may notice that some of their symptoms start to get worse.

An AC unit that isn’t working properly will leave debris and dust in the air that it would otherwise be able to clean out for you.

An AC unit will only help someone with asthma if the unit is well-maintained. That means that the filter is regularly cleaned and replaced as needed. A backward filter will become clogged, leaving the air unfiltered.

4. Your Home’s Air May Not Feel As Clean

The job of an AC unit is to suck in the air in the room, filter it, and blow it out on the other side. When your filter is installed backward, it will quickly get clogged and stop functioning as it should.

Ultimately, the air in your home will be like you don’t own an AC unit at all.


Aircondition Service And Maintenance

To summarize, if you install your AC filter backward, you can expect the filter to get clogged faster and stop functioning. By leaving it in this state, you may end up damaging the entire unit.

Installing the filter correctly is the best practice, but it’s not always easy.

Try looking for arrows that indicate which way to install the filter or compare the new filter to the one you’re taking out of the unit to figure out how it’s supposed to look.

You could always hire a professional, but it’s great to learn how to change it yourself for something like an AC filter.

Frequently Asked Questions

Will Installing a Filter Backward Damage an AC?

If the filter is left the wrong way around for a long period, the debris build-up can make the unit overheat as it works overtime to keep functioning as it should.

It can eventually lead to the unit’s breakdown, but it takes quite a while to get to that point.

Can an AC Unit Really Help With Asthma?

Although we’re no medical experts, numerous studies show that having cleaner air can reduce or help with asthma symptoms.

When an AC unit’s filter is blocked, it stops being able to filter the air as it should, which is why you may notice your symptoms worsening at home.

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