Step-by-Step Installation Guide for Through-the-Wall ACs: DIY vs. Pro Help

❄️ Why Choose a Through-the-Wall Air Conditioner?

Before we jump into the nitty-gritty of installation, let’s take a quick look at why these compact, powerful units have become so popular.

Through-the-wall ACs:
✅ Save valuable window space
✅ Provide quiet, efficient cooling
✅ Are more secure than window units
✅ Have longer service life
✅ Often feature eco-friendly refrigerants like R-32 for reduced energy use

If you’d like to explore the top-rated models, check out the full collection of through-the-wall air conditioners at The Furnace Outlet. You’ll find a range of BTU ratings, price points, and features to suit any room.

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🧭 Installing a Through-the-Wall AC — What’s Involved?

Whether you go the DIY route or hire a pro, proper installation is key to performance. A well-installed unit will:

• Fit snugly with no air leaks

• Drain properly to prevent water damage

• Run efficiently, without straining the compressor

Here’s a step-by-step overview of the process.

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🛠️ DIY Installation Steps

If you’re handy with tools and comfortable working on your walls, a DIY installation is absolutely doable. Here’s what to expect:

📏 Step 1: Gather Tools & Check the Specs

First, read the manufacturer’s installation manual thoroughly. Make sure you have:

• A level, measuring tape, and power drill

• A saw suitable for your wall material

• Weatherproof sealant and insulation foam

• A proper sleeve or wall opening kit

Your AC will also list its required opening dimensions — most units fit into standard sleeves, but double-check the specs so you don’t cut too large a hole.

(More pro-tips on choosing the right unit size and sleeve: see Consumer Reports’ AC sizing guide for help selecting the proper unit BTUs and dimensions.)

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🧱 Step 2: Pick the Right Wall and Prep the Opening

Avoid exterior walls with electrical wiring, pipes, or structural supports that can’t be moved easily. Once you choose the wall:

1. Outline the opening on your interior drywall according to the sleeve template.

2. Cut carefully using a drywall saw.

3. Remove insulation and any interior obstacles.

4. From the outside, cut away siding or brick as required.

(Need help choosing where to place your unit for optimal airflow? The U.S. Department of Energy’s Home Cooling Guide has some helpful placement tips.)

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🧱 Step 3: Install the Sleeve

Slide the sleeve into place and secure it per the manual’s instructions — usually with screws into surrounding studs or a mounting frame.

• Make sure the sleeve tilts 1/4-inch downward toward the outside.

• Fill any gaps with insulation foam and seal the perimeter with weatherproof caulk.

• Proper sealing prevents drafts and keeps water from seeping into the wall cavity.

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🧰 Step 4: Insert the AC and Connect Power

With the sleeve installed and sealed:

• Lift the AC unit into the sleeve (get a helper if it’s heavy).

• Secure the unit with retaining screws or brackets.

• Plug into a dedicated electrical outlet as specified — most require a 230V outlet for higher-BTU models.

• Attach the front grille and test the unit.

(If you’re installing a high-BTU unit, ensure the electrical setup matches the AC’s requirements — check the National Electrical Code for guidelines on dedicated circuits and proper wiring.)

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✅ Step 5: Test for Leaks & Noise

Test the unit’s cooling output and listen for abnormal vibrations.

• Run for 15-20 minutes to verify smooth operation.

• Check outside for water draining properly.

• Adjust the tilt or tighten screws if you detect rattling.

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🧠 Should You Go DIY?

Installing a through-the-wall AC is doable if you have moderate DIY skills and proper tools. However, the biggest risks for beginners are:
❌ Improper framing or insufficient support
❌ Poor sealing, leading to water infiltration and energy loss
❌ Misaligned unit, causing drainage problems

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🏅 When to Call a Pro

If you’re unsure about cutting into your walls or making electrical modifications, it’s wise to hire a licensed HVAC technician or contractor. Pros will:
✅ Handle structural issues (like cutting through brick or siding)
✅ Install sleeves level and secure
✅ Verify electrical requirements
✅ Test and fine-tune your unit for optimal performance

While pro installation might cost a few hundred dollars, it can save you from costly mistakes. Check out Angi’s AC installation cost overview for estimates and help choosing a local pro.

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🧠 DIY vs. Pro Help — What’s Right for You?

Here’s a quick summary to help you decide:

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💸 Save Time & Hassle with Pro Help

Remember, a professionally installed unit often comes with a workmanship guarantee and may keep your manufacturer warranty intact. Even better? Some installers will help you choose the most efficient unit and may offer seasonal deals or rebates.

(Learn more about energy rebates and tax credits for efficient ACs — including through-the-wall models — on the ENERGY STAR website).

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🧰 Savvy Mavi’s Pro Installation Tips

If you do decide to go the DIY route, keep these best practices in mind:

✅ Measure twice, cut once.
✅ Check for hidden wires or pipes.
✅ Keep the unit slightly tilted outward.
✅ Seal all edges against water and air leaks.
✅ Have a helper when lifting the AC into the sleeve.
✅ Test the unit thoroughly before sealing the interior trim.

And if you ever feel in over your head? Don’t hesitate to call in a pro.

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🌟 Final Thoughts

A through-the-wall air conditioner can provide quiet, efficient cooling that integrates seamlessly into your home. Whether you do it yourself or bring in a contractor, a proper installation is key to performance, energy savings, and longevity.

If you’re in the market for a new through-the-wall AC, be sure to check our full collection at The Furnace Outlet’s through-the-wall air conditioners. From R-32-equipped models to ultra-quiet designs, we have the perfect unit for your home.

And remember — Savvy Mavi is always here with practical advice to help you make the smartest, most cost-effective HVAC choices. Happy cooling!