5 Tips on Maintaining Your Window AC

5 Tips on Maintaining Your Window AC

Built to break: every consumer’s three least favorite words. We’ve all had phone batteries give up the ghost the day after our warranty expires or other machines that simply stop working. While there is no International Air Conditioning Illuminati planning obsolescence for window units, many AC units are recycled before it was their time to go. We’ll go over how to maintain your AC unit, so you can ensure your window unit lives a long (and functional!) life. As a nice side bonus, these tips can cut back on your electric bill, help you avoid AC maintenance service, and do right by the earth.


1. Read the Owner’s Manual

According to a study performed by professors from NC State and Rice University, fewer than three out of five people ever open the owner’s manual for a new car. For those three, they only read a little more than half of the manual before tapping out. The owner’s manual or operating guide for an air conditioner is not going to be as long as the booklet for a new car. Take the time to give it a read!

We’re not just saying that because some of us wrote the manual for Windmill. There are features built into most modern air conditioners that are designed to reduce energy consumption by running the compressor less often. Compressors, like all machinery, wear down over time with use. Your owner’s guide should describe different ways to improve operational efficiency, as well as tips for installation and troubleshooting.

If you bought your unit secondhand, or don’t have the manual, try reaching out to the manufacturer for assistance. At Windmill, we have support staff available seven days a week to help with air conditioning unit maintenance. 


2. Maintain the Filter


We’ve waxed poetic on the importance of filters before, so definitely give that article a read for a more comprehensive breakdown. Let’s start with the scary stuff: if the filter on your air conditioning gets too gunked up, your air conditioner will have to work harder to draw air into its system. This overtaxes all that machinery we were just talking about and can even lead to your unit burning out completely.

If you ever see ice forming on your air conditioner, you don’t need to call an AC maintenance service. A clogged filter might be the culprit, so start by checking there. The Windmill has a filter alert that lights up when there’s too much build-up. It’s a good idea to check your filter every month, so you can catch issues before they happen. Examine the filter for any tears before putting it back in your unit.

The Windmill comes with a reusable mesh filter that’s easy to clean off. For units with disposable filters, make sure to keep them stocked and change them every month. You can prevent a lot of air conditioning unit maintenance just by practicing good filter hygiene.


3. Install Your Unit Like a Pro

If you’re wondering how to maintain an AC unit, start from the beginning. Incorrectly installing an AC can cut the unit’s efficiency in half and jack up your energy bill. And as we’ve discussed, the harder your machine has to work, the shorter its operational life. 

Make sure you read the installation guide or owner’s manual for your AC before you begin the installation. Some machines require specific support brackets or have other requirements for installation. You want to ensure the unit sits squarely on the window sill so you can close the window as much as possible. Thoroughly insulate any gaps between your air conditioner and the window frame. Without insulation, any cool air will literally go right out the window.

Where you install your unit also matters. Installing a unit on a south-facing wall, or anywhere that receives a ton of direct sunlight can fry your air conditioner. Inside your home, make sure your AC’s vents are completely unobstructed by any furniture or wall hangings. Make sure to tie your curtains all the way back so they don’t get sucked into the air conditioner by your unit’s fans.

Watch out for branches outside your window. Trim back any tree branches or foliage that gets within a foot of your unit. Blocking the exhaust vents can cause your unit to overheat or grow mold. The mold grows when the moisture your unit produces gets trapped inside. Mold is gross, and also really bad for the more delicate components with an air conditioner. 

If you have weird windows or aren’t comfortable with DIY projects, consider hiring a pro to install your air conditioner. At Windmill, we offer premium installation for customers who live by us in New York City, and have paired nationally with TaskRabbit to make sure our customers can get their air conditioner in their window. Installing your air conditioner correctly will save you headaches and AC maintenance service down the road.


4.  A Clean Machine is a Healthy Machine

If some of these tips on how to maintain an AC unit sound suspiciously like how to clean an AC unit, well, you caught us. Keeping your unit clean helps with operational efficiency and helps preserve your unit’s internal machinery. We’ve already discussed how crud building up on your filter hurts your AC, but the same is true for its vents, as well. 

Use a damp rag to clean dirt and other debris off the vents off your unit. It’s not just unsightly—dirt and other debris will enter your unit through the vents, and then ricochet around inside, damaging different components. Remember that mold we talked about earlier? If too much moisture accumulates in your AC, it might start producing slime.

Okay, enough of the horror talk: how do we deal with it? If you can see standing water in your unit, first, find a helper. With your helper, carefully raise the window sash and tilt your unit backwards so the water empties out. Just make sure there’s no one below you before you start tilting! 

If there’s some type of fungal growth in your unit, dilute half a cup of bleach in a gallon of water. Remove your unit from the window and set it on some towels or newspaper. Carefully pour the solution into the unit via the vents. Tilt the unit to empty out any of the solution and let it dry completely before putting it back in the window and resuming cooling.

When you store your AC, wrap it in a protective cover before putting it in a box. This way, you’ll have two layers of protection against dust, moisture, and impact damage. We go into more depth on storing your air conditioner here. If your air conditioner has been off for a prolonged period of time, dust the vents and grille before powering it on. 

Improperly storing your unit or letting your AC get filthy will result in a call to an AC maintenance service, or having to replace your machine. The old platitude is that “Cleanliness is next to godliness.” We won’t go that far, but you skip a lot of air conditioning maintenance just by keeping your unit clean.


5. Run Your Machine Through the Paces

If you’ve ever seen a basketball team warm up before a game, you’ve seen them do a few different drills to loosen up. They’ll shoot their jumpshots and run layup lines, in addition to stretching and jogging around the court. By activating different muscle groups with different exercises, the players prime their bodies for undergoing many different kinds of stress.

Your air conditioner is the same way. Once you figure out the perfect settings for running your AC, it’s still worth running your unit on different modes and fan speeds for short periods of time. To clarify: if your AC, like the Windmill, has three different modes, run it on all three modes for at least five minutes each month it’s in operation. Engaging different parts of the air conditioner will dislodge and build-up inside the unit and test functionality. Understanding how your unit works will help you understand how to maintain AC units in general.

If you notice any issues with your unit, consult your owner’s manual or reach out to customer support. Continuing to operate the unit despite known issues will cause further problems down the road, and shorten your AC’s lifespan.


The easiest way to handle air conditioning unit maintenance is by building good habits. Get in the habit of checking your filter each month to prevent filter buildup. Get in the habit of cleaning your machine to keep debris away from the internal components. And please, get in the habit of reading the owner's manual. The manual will be specific in telling you how to maintain your AC unit, specifically. 

We’ve described ACs oozing mold and pebble ricochet; these are relatively extreme issues with an air conditioner. And yes, following our maintenance tips will prevent your AC from looking like a Goosebumps cover. But more importantly, by building good maintenance habits and taking care of your machine, you’ll ensure that your AC will operate at its peak for years to come.