Photo of a Window Air Conditioner
Image by Inga Munsinger Cotton | CC BY 2.0

Chances are you would love to stay cool during summer, but are you sure your window air conditioner is in a good state?

The last thing you want to experience in the middle of the heatwave is a breakdown of your air conditioner.

Luckily, you can avoid this by doing periodic maintenance of your air conditioning system.

Besides preventing downtime, proper maintenance will also prolong the life of the window air conditioner, eliminate costly repairs, and reduce energy consumption.

With this in mind, understanding how to maintain a window air conditioner (especially if you recently bought it) at the start and end of a cooling season is essential to keep it running efficiently for a lifetime.

Here are some of the most important window-mounted air conditioner maintenance tips to help you out.

And, if you’re looking for a new unit, be sure to check out our guide on the best rated window air conditioner here. It includes the best models for every price range and room size.

How to Maintain a Window Air Conditioner

Clean and Replace the Air Filter

Although it plays a critical role in your air conditioner, the air filter is probably one of the most overlooked aspects of air conditioning unit maintenance.

According to Energy Saver, you can save up to 15% of the energy consumption cost when you replace a dirty or clogged filter.

For optimal efficiency, you should clean the filter once a month during the operating season. You can do it more frequently if you are allergic or have pets in the house. To clean the filter, you need to remove the front panel to access it then use warm water and dish soap or vinegar to clean. If your filter has some holes, tears, or other damages, then you should instead replace it.

Check and Clean Condenser Coils Each Season

Dirt builds up over time, especially on the inner part of the condenser coil, when you use your window air conditioner continuously.

Accumulation of dust or dirt leads to inefficiency which means that your AC will have to work more to remove heat. This will ultimately translate to higher energy consumption.

You can solve this by inspecting and cleaning both the evaporator and condenser coil at the start of the summer.

It is recommended to use a bristle brush and a vacuum cleaner to clean these parts.

You might need to remove these units from the casing for a more thorough cleaning. Make sure to remove the lint or dirt that might have built up on the bottom side of the conditioning unit. This will ensure the condensing fan blade slinger will pick up condensate water with ease.

The best time to do a thorough clean would be the start and the end of the cooling season. As you clean, please take great care because you can easily bend the aluminum coil fins.

Inspect for Insects and Animal Nests

Inspecting for insect and animal nests is useful, especially when you have left your window air conditioner uncovered during the winter.

You should check for common occurrences like bees, spiders, and rodent nests on the internal part of the conditioner and remove them.

The best way to avoid this is to store your air conditioner in a protected space. And, if you must leave it on the window, you should cover it.

Check the Coil Fins

Another unit that can affect the efficiency of your air conditioner is the coil fins. The coil fins can easily bend. The good thing is that you can restore them effortlessly using a fin comb.

In addition to this, you should also check on coils on the front of your air conditioner for ice buildup.

Sometimes, when the outside temperature becomes cool (60 degrees Fahrenheit or lower), the ice buildup which, in turn, impair the normal operation of the conditioning unit. It is best to avoid using the air conditioner at these temperatures.

Inspect and Clean the Water Pan

Another routine cleaning tasks that you have to do during the season is to clean the inside base, especially the water pan.

This will prevent the development of musty odor and mold. To carry out this process, you need dish detergent and warm water. You can also use vinegar instead of detergent.

Replace Batteries in the Remote Control

This might seems like an obvious thing, but if your air conditioner comes with a remote control and it fails to work properly, it may be because the remote control is using old batteries.

Make sure, each season you replace the batteries of your unit’s remote control.

Find a Suitable Storage Place

You should ensure that the place you store your air conditioner is free from pests, small animals, and moisture conditions.

Some suitable places to consider are the basement, attic, and utility room.

You should avoid garages because a majority of insects and small animals like to seek shelter there. The insects could find their way to the internal part of the AC unit.

Likewise, rodents and mice are notorious for chewing the wiring, which can cost you a lot to repair.

Pre and Post-season Preparation/Maintenance

The best way to avoid most complications associated with air conditioner efficiency or breakdown is to do a full inspection before and after the cooling season.

This means all the routine maintenance activities should be done before storage of your unit.

You should also inspect the window seals to ensure there are no gaps that will let cool air out or let outside contaminants to enter.

If you are using the unit for an extended period then, you should ensure that it is covered during the winter season. Use a suitable its cover or any other all-weather material that can securely fit the unit without interfering with the airflow.

Other Maintenance Issues

If the above maintenance routines are not sufficient to keep your unit running smoothly, you should consider enlisting service of an HVAC technician.

These professionals know everything about how to maintain a window air conditioner.

Sometimes, your window air conditioner might develop other problems even after the regular maintenance. These professionals will most likely test the refrigerant leaks, check refrigerant levels, check the belts and fans, measure the airflow in the evaporator coil, lubricate the motor, and ensure all the electrical units are functioning.

If worse comes to worst, you may need to purchase a new window-mounted air conditioner. Hopefully, it doesn’t come to that, but if you do find yourself in this situation, you can find our window air conditioner reviews here.


In most cases, if you implement most of the above window air conditioner maintenance tips, you are less likely to require the services of an HVAC technician.

The best way to approach it is to always check the owner’s manual for step-by-step instructions before starting any maintenance or repair work.

If you notice any major defects on your air conditioner and the manufacturer’s warranty has not expired, please reach out to them to see if they can resolve the issue.