🧭 Introduction: Keeping Your Through-the-Wall AC Going Strong
Hey everyone — Mark Callahan here.
If you own a through-the-wall air conditioner, you already appreciate its compact design and powerful cooling. But like any mechanical equipment, these units need regular attention to stay in top shape.
By performing simple maintenance and knowing how to troubleshoot common problems, you can extend the lifespan of your AC, reduce repair bills, and keep your home comfortable all summer long.
In this article, I’ll take you through the must-know maintenance practices and easy fixes for common AC hiccups. Whether you’re handy with tools or just looking to understand the basics, you’ll leave here knowing how to help your unit go the distance.
And if you’re looking to upgrade or buy a new unit after reading this, you can always browse our selection of efficient through-the-wall air conditioners at The Furnace Outlet. Ready? Let’s dive in.
🧹 Why Routine Maintenance Makes a Difference
Routine maintenance isn’t busywork — it’s essential to prevent problems and maximize efficiency. According to the U.S. Department of Energy (DOE Energy Saver), properly maintaining your AC can improve its efficiency by up to 15%. That’s a significant savings on your energy bills!
More importantly, a well-maintained unit can last 10–15 years, sometimes even longer — versus one that’s ignored and burns out early.
Here are a few big-picture benefits of staying on top of maintenance:
✅ Fewer emergency repair calls
✅ Better energy efficiency and lower utility bills
✅ Improved cooling performance
✅ Longer unit lifespan
✅ Healthier indoor air quality
🧽 Key Maintenance Tasks for Every Season
Here’s what I recommend you do each season to keep your unit humming:
🌸 Spring & Summer Routine
🧼 1. Clean or Replace Filters
Your filter is the first line of defense against dust, pet dander, and allergens.
Clean filters improve airflow and cooling power — while dirty filters reduce efficiency and strain the compressor.
Recommended:
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Clean washable filters monthly with mild soap and water.
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Replace disposable filters every 1–3 months.
For more guidance, check the EPA’s tips on filter maintenance at EPA.gov.
🧹 2. Clear Debris Around the Outdoor Grille
Leaves, grass, and debris can block the outside grille and choke off airflow.
Quick fix: Check the exterior portion of the unit every month — sweep off debris, trim grass, and make sure there’s at least a 12-inch clearance around the outside vent.
💧 3. Clean the Drainage System
Through-the-wall ACs remove humidity, so proper drainage is critical.
If water pools inside the unit or around the base, it can cause rust and mold.
How to clean it:
✅ Locate the drain hole and pan.
✅ Flush with warm water.
✅ Remove algae with a diluted vinegar solution.
🍂 Fall & Winter Routine
🧼 1. Inspect and Clean Coils
Over time, the evaporator and condenser coils accumulate dust that reduces heat exchange.
Use a soft brush or vacuum attachment to gently clean the coils at the end of the cooling season.
🧣 2. Insulate for the Off-Season
If you live in a colder climate, protect your unit from drafts and moisture during winter.
Cover the exterior with a waterproof AC cover — or use an insulation panel inside the sleeve.
And if you’d like to see a visual demo of proper end-of-season AC prep, Hunker has a great article on winterizing window ACs that also applies to wall units: Read their winterization guide.
🧰 Common Troubleshooting Scenarios & Quick Fixes
Every AC will eventually act up — that’s just part of owning one. Here are some common issues and solutions you can try before calling a pro:
❄️ AC Runs but Doesn’t Cool
Possible causes:
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Clogged filter
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Dirty condenser or evaporator coils
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Low refrigerant
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Poor insulation or leaks around the sleeve
Quick fix:
✅ Clean or replace the filter
✅ Gently clean the coils
✅ Check that all seals around the unit are tight
If those steps don’t help, you might have a refrigerant issue. According to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) (learn more at ASHRAE.org) refrigerant handling should always be left to a qualified HVAC technician.
💧 Water Leaking Inside
Possible causes:
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Blocked drain holes
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Improper tilt of the unit
Quick fix:
✅ Clear any drain holes with a small wire brush
✅ Make sure the AC is slightly tilted downward (towards the outside) for proper drainage
✅ Consider using a level to check the tilt — most units require a very slight slope outside
🔇 Excessive Noise or Vibration
Possible causes:
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Loose mounting screws
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Worn rubber isolation pads
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Fan blade hitting debris
Quick fix:
✅ Check and tighten all mounting hardware
✅ Inspect fan blades for obstructions
✅ Replace damaged rubber pads if needed
⚡ AC Trips the Breaker
Possible causes:
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Overloaded circuit
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Dirty filter or coils
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Faulty wiring
Quick fix:
✅ Reset the breaker and reduce other appliances on the same circuit
✅ Clean the filter and coils to reduce load
✅ If it keeps tripping, contact a qualified electrician — electrical issues require an experienced hand
🧰 Prolonging Equipment Life with Smart Usage Habits
Your day-to-day habits also play a big role in the lifespan of your AC. Here are some pro tips for maximizing performance:
✅ Use a programmable thermostat — Avoid extreme temperature swings that force the unit to work too hard.
✅ Run ceiling fans — Improve air circulation so the AC can cycle less often.
✅ Close blinds and curtains — Reduce heat gain during the day and take some load off the unit.
✅ Avoid putting heat-producing appliances (like lamps and computers) right next to the thermostat.
If you’d like to explore energy-saving habits in detail, check out the U.S. Department of Energy’s energy-saving guide at energy.gov.
🏡 When to Call in a Pro
Routine maintenance and basic troubleshooting go a long way — but some jobs require a trained technician.
Here are a few signs it’s time to call the pros:
🚨 AC blowing warm air despite clean filters and coils
🚨 Ice forming on the evaporator coil
🚨 Unusual noises like grinding or screeching
🚨 Burning smells or repeated circuit trips
🚨 Water leakage that keeps recurring
If you ever feel out of your depth, play it safe and call a licensed HVAC technician.
🏅 Conclusion: Care for Your Through-the-Wall AC — It’ll Return the Favor
A little TLC goes a long way when it comes to extending the life of your through-the-wall air conditioner. With regular filter cleanings, coil care, proper drainage, and some smart habits, you can keep your unit cooling efficiently — and save yourself the cost and hassle of premature replacement.
And if you’re ready for an upgrade or need a dependable new model, remember to browse the full selection of energy-efficient, R-32-equipped units at The Furnace Outlet’s through-the-wall AC page.
Have questions or want help choosing the perfect model? Drop me a note — I’m here to help you stay cool and comfortable for years to come.
