🌟 Introduction: Why Maintenance Matters
When summer temperatures rise, there’s nothing quite like the crisp, cool comfort of a properly functioning air conditioner. But like all appliances, a through-the-wall AC unit needs regular care to run at its best.
Without periodic maintenance, dust and debris can clog filters, coils can freeze up, and your energy bills can creep higher and higher — all while putting extra wear and tear on the unit itself. Fortunately, keeping your AC in great shape doesn’t require a degree in HVAC repair. With some simple tools, a little bit of time, and this easy-to-follow guide, you can keep your through-the-wall AC humming efficiently for years.
In this article, I’ll cover all the basics, from simple cleaning routines to recognizing when it’s time to call a professional. Let’s dive in!
🧹 1. Cleaning or Replacing the Air Filter
Your air filter is your AC’s first line of defense against dust, pollen, pet dander, and other airborne debris. When the filter becomes clogged, the unit has to work harder — reducing efficiency, stressing components, and driving up energy costs.
✅ How Often Should You Check?
You’ll want to inspect the filter at least once a month during the cooling season and clean or replace it as needed. Filters may require more frequent attention if you have pets or live in a dusty environment.
Cleaning reusable filters:
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Turn off the unit and unplug it.
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Remove the front grille or filter panel.
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Vacuum the filter with a soft brush attachment.
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Wash the filter gently in warm water with a mild detergent.
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Let it dry completely before reinserting.
Replacing disposable filters:
If your unit uses disposable filters, follow the manufacturer’s instructions for finding the correct replacement size and style.
And if you want to explore other tips for improving indoor air quality, check out this detailed guide from the EPA on improving indoor air.
🧊 2. Keeping the Coils Clean
Your through-the-wall unit contains two sets of coils — the evaporator coil (inside) and the condenser coil (outside). Both need to be kept clean for the unit to run efficiently.
🧽 How to Clean the Evaporator Coil
The evaporator coil is often behind the front grille.
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Turn off the power and unplug the unit.
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Remove the front panel carefully.
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Use a soft brush to gently remove dust buildup.
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Spray the coil with a no-rinse coil cleaner (available at most hardware stores).
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Let the unit dry before reassembling.
💧 Cleaning the Condenser Coil
This is especially important if your unit’s exterior face is exposed to dirt, pollen, or salt air.
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Shut off the power at the breaker.
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Remove the unit’s casing or the protective cover.
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Gently brush or vacuum off loose debris.
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Rinse the coil carefully with a garden hose at low pressure — never use a pressure washer, as it could damage the fins.
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Let everything dry before turning the unit back on.
When you keep the coils clean, the refrigerant can do its job — cooling the air efficiently and using less energy.
🔧 3. Straighten Bent Fins
The tiny aluminum fins on the condenser and evaporator coils help transfer heat. Over time, they can bend and restrict airflow. Fortunately, fixing bent fins is easy:
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Pick up a fin comb at your local hardware store.
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Gently run the comb across the fins to straighten them.
This small step can improve your unit’s airflow dramatically.
For more expert insight into coil maintenance and other cooling tips, see this article on AC care from This Old House.
🏡 4. Check the Unit’s Drainage
Your air conditioner removes humidity as it cools — that water has to go somewhere. Normally, it collects in a drain pan and exits through a drain hole. If that drain hole becomes clogged with debris or algae, water can back up into your home or cause rust inside the unit.
Here’s how to keep drainage clear:
✅ Locate the drain hole at the bottom of the unit.
✅ Use a small brush or pipe cleaner to gently remove any debris.
✅ Test drainage by pouring a small amount of water into the pan and ensuring it flows freely.
You can also use a 50/50 vinegar-water solution to prevent future algae buildup.
And for more home cooling maintenance ideas, check out the practical advice at the Department of Energy’s energy savings site.
⚡ 5. Inspect and Tighten Electrical Connections
Electrical components are at the heart of every AC unit — and they deserve attention too. Loose wires or corroded connections can lead to poor performance or even safety hazards.
🧰 DIY Inspection Steps:
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Cut the power at the breaker and unplug the unit.
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Remove the electrical panel carefully.
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Look for wires that appear frayed, loose, or burnt.
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Use a screwdriver to tighten any loose terminal screws.
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Replace damaged wires or contact a professional if you see signs of serious wear.
If you’re not comfortable working with electrical components, it’s always better to call in a licensed technician.
🧠 6. Test the Thermostat and Controls
Your unit’s thermostat and controls may seem like small details — but they can have a big impact on comfort and energy use.
Here’s what to do:
✅ Set the thermostat a few degrees lower than room temperature and listen for the unit to click on.
✅ Adjust fan speeds and mode settings to make sure each one responds properly.
✅ Replace the remote control batteries every 6-12 months.
✅ Consider upgrading to a programmable thermostat or smart control for automated temperature control and energy savings.
If you’d like to explore the benefits of upgrading to a smart thermostat, check out this article on programmable thermostats at the U.S. Energy Star site.
🌡️ 7. Know When It’s Time for Professional Help
While regular maintenance can prevent most problems, there are times when it pays to call in a pro. Reach out to a certified HVAC technician if you notice:
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Strange noises like grinding, banging, or hissing.
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Unusual smells like burning or mustiness.
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Refrigerant leaks or ice on the coils.
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Rapid cycling on and off.
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Weak airflow or warm air blowing from the vents.
A trained technician can test refrigerant levels, repair leaks, and fine-tune the unit for maximum efficiency — ensuring it stays in top condition for years to come.
💸 8. Save Money With Routine Maintenance
By keeping up with regular AC care, you’ll:
✅ Lower energy bills — a well-maintained unit can use up to 15% less energy.
✅ Avoid costly repairs — small tweaks now prevent big breakdowns later.
✅ Extend your unit’s lifespan — most through-the-wall units last 10-15 years with proper upkeep.
✅ Enjoy more consistent cooling — keep your family comfortable all summer long.
🏆 Conclusion: Cool, Confident, and Energy-Wise
Proper maintenance is one of the easiest ways to ensure your through-the-wall AC stays dependable and efficient for years to come. From regular filter checks to coil cleanings and professional tune-ups, these simple steps will help you save money, reduce energy use, and breathe easier in your home.
And when it’s time to upgrade? Shop our carefully curated selection of high-quality, energy-efficient through-the-wall air conditioners — designed to keep you comfortable, season after season.
With a little know-how and TLC, your AC will continue to keep you cool for years to come!
