Window AC Unit Maintenence

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Updated August 19, 2022

It doesn’t matter if you’ve got the best air conditioner out there; nobody likes powering on their AC to find it sputtering and blowing warm air in the heat of summer. Failing to maintain your unit will result in this exact scenario. But good news! Window AC unit maintenance is generally simple.


  • Proper AC maintenance increases a unit’s lifespan, energy efficiency, and cooling power.
  • Routinely cleaning the air conditioner filter is the primary way to keep the unit running properly.
  • Make sure to remove debris or dirt buildup from the drain ports and the fins to keep the unit at max cooling capacity.

Below, we’ll go through the most common maintenance steps for window units so that you don’t have to stand in front of an open freezer in mid-July. And if you find that your unit is too far gone, check out our picks for the best energy-efficient window air conditioners available.

Insider Tip

Proper storage is key to preserving the quality of your window AC unit. Always clean and drain your unit and any clogged filters before storage. Then, store it in a dry place that won’t drop below freezing.

Maintaining Your Window Air Conditioner

There are many types of air conditioners, all of which require upkeep. Window AC units need specific care if you want to keep them running correctly for a long time. So if you’ve been asking yourself questions like, “Why is my window air conditioner freezing up?” you likely have a bit of work to do on your AC. Fortunately, the steps below are simple but must be done routinely for the best results.

Now, if you’re having issues with a central AC unit, you may want to read our articles on why your air conditioner pipes are freezing. Or, if you simply want to further your AC knowledge, read up on the differences between aluminum vs copper air conditioner coils.

Check the Air Filter

Failing to keep a clean filter is a common cause of AC malfunction, from a loss of air quality to reduced airflow. Cleaning the filter also prevents frozen evaporator coils, decreases your energy bills, and allows the unit to stay at maximum output. To add to your regular maintenance routine, you can invest in cloths and condenser fin brushes that can effectively clean dust and debris from a dirty air filter within an appliance like a window air conditioning unit. A soft-bristle brush will keep the unit clean while also being gentle on the AC’s internal components like sets of coils.

If you have a reusable filter, wash it monthly with soapy water. If while washing the filter with water, detergent, and a damp cloth, you notice your water turns into dirty water, change out the water. Let the filter dry completely before placing it back into your air conditioner. If your filter is disposable, you’ll need to buy and install a new one.

Of course, if your unit is too far gone, it may be time to check into when a home warranty will replace an air conditioner.

Clean and Repair the Fins

Checking the aluminum fins is a great thing to do before using your AC unit for the first time every summer. First, examine the fins at the back of the unit and see if they are bent or dirty. If dirty, wash with warm water and mild soap. For any bent fins, you can purchase a tool called an AC fin comb to straighten the fins. Ensuring the fins are clean and straight increases the air conditioner unit’s efficiency while decreasing energy consumption.

Clean and Empty Drain Pans and Ports

Each window AC unit has a drain pan that collects condensation from the condenser coils. You should check this twice a year — in the spring before you turn it on for the first time and again after summer is over and you’re getting it ready for winter storage.


Failing to clean your air filter causes dust particles in the unit’s airflow, resulting in lower indoor air quality.

Ensure that the pan is clean, and the drain port is not clogged. You may also want to check this every few weeks over the summer to avoid other issues, such as mildew and mold growing inside the unit.

STAT: Keeping a clean energy filter can help homeowners save up to 15% on monthly energy bills. (source)

Window AC Unit Maintenence FAQs

What is the average lifespan of a window air conditioner?

The typical lifespan of a window Ac unit is 10-20 years.

What should I do if my AC fins are bent?

It's best not to run the unit with bent fins. If the fins are bent, remove the unit from the window. Then, run a fin comb through until they are straight.

How do I calculate the correct size window air conditioner unit for a room?

To calculate the right size, you have to take the room's square footage and compare it to the level of BTUs. It's also wise to factor in ceiling height and quality of insulation.
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