Portable Window AC Security – Air Conditioner Lock, Bars, Cage

Window Air Conditioner Security

How to secure a window AC unit…

During the summer months, window AC security is important. When the weather warms up, it’s time to install your window air conditioners. But they can become a target for burglars.

A burglar could get into your home through a window after pushing in the air conditioner on the 1st-floor. Or the burglar might just steal it!

Here’s what you can do about it. I’m going to list a number of tips and things you can do to help with window air conditioner security.

Read on for several up-to-date suggestions!

Screw the Top Mounting Rail Window AC unit into Sash

This works for wood windows (see below for vinyl or metal), and other options.

Most window air conditioners are installed and simply held in place by gravity. It’s tucked behind the window sash which keeps it from falling out. Maybe there’s a small screw holding the top rail and a few on the side for the accordion side-panels.

Many people don’t even install a single support screw into the top rail because the air conditioner is held in place by gravity and its downward force against the window sash. Good enough, right?

So, what can you do to better secure your window air-conditioner?

At least install a screw through the air-conditioner’s top mounting rail into the window sash. Most window air conditioners include a drilled-out hole in the top center to accommodate this.

Consider drilling additional holes through the same top mounting rail to accommodate more screws into the lower window sash (see illustration below).


UPDATE: If you cannot screw into the window, there are several alternate ways to secure the air conditioner which I’ve listed below. One of which is this clever little bracket that will keep the AC unit from being pushed out:

Stabilizer Pack

To install the security bracket, the AC was positioned properly in the window and the small u-shaped end of the bracket was placed over the upper flange (support bar) of the air conditioner.

The window was then closed over the large u-shaped end of the bracket.

Thin weather stripping was placed between the window sash and the upper flange of the air conditioner to seal the small gap (due to the thickness of the bracket).

The bracket was secured to the flange of the air conditioner by tightening the provided bolt through the bottom hole. The bolt wasn’t overly tightened since it essentially prevents the bracket from sliding too much forward and back.

(I didn’t use the bolt in the top hole since the air conditioner flange was too high.)

Although the bracket looks to be a bit loose, it can’t be removed and the air conditioner can’t be pushed out of the window unless the bottom sash is raised.

The provided window locks didn’t work for my windows, so I used the Windobully Window Lock to prevent the sashes from being raised or lowered.

~ from a product review

Install Security Window Lock for your Portable Air Conditioner

A convenient window lock for air conditioner security: (Sliding Window Lock, Window Stop, Window Restrict)

A window lock will prevent or deter the burglar from pushing and forcing up the window.

The AC unit may be screwed to the sash, but if the window itself isn’t locked it’s still possible to force open and reach in and shove the air conditioner. Install window frame locks to prevent this.

AC Window Lock – Vinyl & Aluminum

For Vinyl Windows – you might consider this popular window lock as shown below:

>> Defender Security Sliding Window Lock for Vinyl Windows
(view on amzn)

>> Defender Security Sliding Window Lock, Aluminum

Sliding window lock for vinyl windows

Window Security Wedge

Another clever idea is a window wedge.

>> Window Stopper
(view on amzn)

Window Lock Wedge

Window Air Conditioner Security Bars

This adjustable window security bar is designed to fit between the window and the top frame to prevent it from opening beyond an adjustable opening distance. Perfect for when a portable AC is installed.

The security bar fits into the gap. Measure the gap and be sure you purchase the right security bar for that measurement.

Here’s an example of what I’m talking about:

(Measure the gap with the AC installed to determine which security bar will fit)

>> EZ-AC Window Security Bar – Extends 7 1/2″-14″
(Made in The U.S.A. by Veteran Owned Business)
(view on amzn)

Here’s another one:

>> Sturdy Steel, Extends from 15 1/2″ to 29 1/2″
(view on amzn)

>> Sturdy Steel, Extends from 7 3/4″ to 14 3/8″

‘Do It Yourself’ Window Security Bar:

While the air conditioner is mounted in the window, measure the distance from top of the lower window frame to the very top of the double-hung frame itself (with AC installed). Cut a wooden dowel to snugly fit – which can be wedged to prohibit the window from opening further…

Window Air Conditioner Bracket

It’s also a good idea to get a window air conditioner bracket. It makes it harder for the burglar to get the air conditioner out from the outside. You could also secure the portable AC unit to the bracket in various ways.

>> Brackets on amzn

Stick-on Window Alarm

Here’s a great product that will absolutely deter a would-be burglar.

The second they begin to force open the window, this cleverly designed window alarm will alert (based on motion/vibration sensing).

It simply ‘sticks’ onto the window, inside. Small, only about 3″ diameter. It has an ‘on/off’ switch for your convenience when opening the window yourself…

>> Window Alarm 4 Pack – Loud 120dB Alarm and Vibration Sensors
(view on amzn)

Stick-on Burglar Alarm Security Window Sticker Decal

Deterrence! On the window with the air conditioner, stick on a home security window decal where it will be plainly visible.

This alone may be enough to prevent a break-in as the burglar may move along to an easier target.

>> Home Security Yard Sign and 4 Security Sticker Window Decals
(view on amzn)

Brinks window decal

Window AC Accordion Side Panels

Depending on the width of the window air conditioner, the ‘accordion’ side panels may be extended fairly wide, or maybe not. This is an obvious weak point of entry for a burglar to punch through and gain leverage to shoving the air conditioner itself.

While the aforementioned suggestions will slow down or deter a burglar (likely to the extent of giving up without attracting attention), you might consider to (do it yourself) build wooden side panels to replace the plastic ‘accordion’ panels.

Window Air Conditioner Security Tips

Ultimately, you are not going to stop a determined burglar. But you will probably stop the majority of amateur burglars who are looking for quick and easy entry.

If one of them happens to pick your home because they see a window air-conditioner hanging out of a 1st-floor window, when given a hard push and it doesn’t budge, they will probably move on.

If the burglar pulls or pushes on the air conditioner while attempting to lift the window sash, it will not readily come if you’ve taken the precautions mentioned above.

Burglar Proof Tips

Okay, maybe more accurately stated, burglar resistant…

Tip: Consider removing any 1st-floor window air-conditioners when going on an extended vacation. A few minutes effort may be worth it…

Tip: You could plant thorny bushes… rose bushes, blackberry bushes etc. just below your windows…

Replace the side panels with plywood between the sash and jamb.

A wire cage to cover the outside of the AC unit.

Amazon Recommends this Air Conditioner:

Perfect for a bedroom, a small room, great reviews:

Have it shipped right to your door:


Air Conditioner recommended by Amazon

More security-related articles:

3 Ways A Burglar Breaks In, 80 Percent Of The Time

7 Mistakes That Burglars Love You To Make…

10 Tips For Better Home Security


  1. Been there done that : )

    My window was a slider v up/down. I did lock myself out, couldn’t find the spare key that was in the bush and so thought that I could get in without doing any damage. Wrong.

    The ac unit hit the floor before I could react. Put a pretty good dent in it but didn’t damage the window. After that, seeing how easy it was I did a better job of bolting it down.

  2. I found a latch that you can attach to the top window that has a wedge shaped cover that can be opened flat to open the window the full way. With the cover in place, it limits the travel of the upper & lower windows to whatever height you install it at (I did 4″).

    I know Anderson has an expensive version of the same thing on Amazon, but the inexpensive version at WallyWorld had done the job find for me.

    Hope this makes sense, will try to find a link…..

  3. I’ve updated this article for the 2020 season – Window AC security for portable air conditioners. The article has been popular in search-engine-land, so if you have further suggestions – let’s hear them…

  4. Unfortunately, we have those casement windows that crank out sideways. I wouldn’t mind having just one or two window units so we wouldn’t have to run the whole house AC. I did find out there are small stand alone units for individual rooms. Might try one of those. And they are on wheels, so you can move them from room to room. They look like a tall room air purifier.

    1. DJ5280,

      I have one of those stand alone units for the few times it gets unbearably hot here. It definitely helps. One thing to be aware of that you might have to find a work around for. These are portable in the sense that you can roll them anywhere, but, they must be vented to the outside when in use. The venting set-up is geared for double hung windows – adjustable sliding sides with a hole for the vent tube to attach to. I don’t see how that would work with a casement window. If you knew where you wanted it, and were handy in the carpentry area, you could always create your own venting to outside.

      1. I had purchased two of those roll-around AC units several years ago when we were renting an A-frame home during an interim 2 year period prior to landing at our current AO. Regular portable window AC wouldn’t fit the crank-out casement windows. Regarding the venting for the roll-around units, I had to build it (plywood) to fit a given window. It wasn’t terribly difficult, but it was the only way for it to install and function properly.

  5. Believe it or not, thieves will even steal a big Central Air unit for the copper it contains. I recall living in Orlando Fl. about 15 years ago and the City planted a bunch of new trees along the I-4 interstate. Later that week (2 am) they caught a gang digging them up to resell. Yes, window units say, ” Please steal me!, or break in for even better stuff”.

    1. My point is, folks will steal anything. Example: DW sold medical equipment (Pulse Oyx’s) in south Florida. The medical students/ future Doctors used to steal $3,000 pieces of equipment from the Operating rooms at night so they didn’t have to buy them when they opened their own practices.

    2. S.W.,
      You will find in any big city or suburb (with a big drug problem) that empty houses will usually be vandalized by having all the copper stripped out, electrical wiring, copper plumbing, AC copper tube sets. I’ve even heard of this happening in some mines that had been closed, where people would steal copper trolley and power cable for the copper. (then again i have also heard of several cases where they found said thieves dead inside the mine from the effects of bad air. That taught them a hard lesson.)

  6. S.W.

    One of the nice things about the portable inside units is the only thing possibly visible from outside is the vent opening – nothing sticks out. For less visibility, one could vent from a window/side of the house that is more hidden from public view.

  7. Gee, didn’t even know that about the venting issue. Thanks all. Guess we’ll stick with the central air. Good thing it’s been a cool spring and haven’t needed it yet. Got enough on my plate right now…..

  8. I had brand new vertical double sliding windows installed. Each side can slide open. When putting in my portable a/c vent, there is no way to lock both windows. If I put a lock on the inside window the other outer window can still be slid open. Wish I knew that before spending thousands on new windows.

  9. Seattle Rain,
    If the windows are running in a slide there is fix. You could put a stick in the track of the outside window, from the inside to keep it from opening more. Then Lock the inner window.
    If worse comes to worse, you can always drill a 1/8″ hole through the track into either one or both windows and put a small screw in there to lock them “in their tracks”, or a screw in the bottom of the track that sticks up to stop the window. If you are worried how well these will hold up, well…. if anyone is really desperate they will just break the window and have off with your AC unit, or climb in. Just take some time to look at it, you’ll find a way to lock both in place. Good luck.

    1. Minerjim,
      yes sir, unfortunately windows are the weak point in any home security system. three locks on every door and they can still get past it with a rock or crowbar through a window. ya can’t stop them. all we can do is slow them down. especially in the boonies. where i live people could back a u-haul up to the front door, load everything and no one would see them, i practice armed vigilance. door locks only keep an honest man honest.
      hell, i don’t go anywhere now anyhow. i can’t imagine why i would want to except for going to the river behind the place and the county board meetings once a month, that’s my day to go to town. UPS has figured out where i live if they don’t switch drivers : )

      1. Scout,
        Yeah, ’round here every farmer carries a gun and crooks know it. The criminal critters know unless it is a quick grab and dash, they stand to shot. Our sheriff frowns on criminal trespass. It is only in the towns where the police have issues, where crime is up. In the country…..we got backhoes and hog feeders.

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