Installing a Through-the-Wall AC? Here’s What to Expect (And How to Prep)

👷♀️ Ready to Cut a Hole in Your Wall (on Purpose)?

I know, it sounds intense. But hear me out: installing a through-the-wall AC isn’t as scary as it sounds — if you know what to expect and plan ahead.

Whether you’re hiring a pro or feeling DIY-confident, this post covers:

• Tools and prep work

• What a wall sleeve does (and why you need one)

• How long it takes

• What mistakes to avoid

• And of course, what to budget

Let’s get into it — because smart installs = cooler summers and zero regrets.

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🛠️ Step 1: Know What You’re Getting Into

Installing a wall AC is different from sliding in a window unit. You're cutting a permanent opening into your wall, so the install is more involved. Here's the high-level checklist:

• ✅ Choose the right BTU size for your space

• ✅ Buy a compatible wall sleeve (check your AC’s specs — most need a universal 26" sleeve)

• ✅ Pick your wall carefully: avoid plumbing, gas lines, and load-bearing studs

• ✅ Know your electrical needs — most 8,000–12,000 BTU units are 115V, but some larger ones need 220V

Still not sure which wall is best? Talk to your HVAC installer, contractor, or super before cutting.

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🧱 Step 2: Install the Wall Sleeve

A wall sleeve is like a mailbox slot for your AC — it protects your unit from structural damage, moisture, and debris. It also keeps cold air in and pests out.

Here’s what to know:

• Most sleeves are metal, weather-sealed, and insulated

• They’re designed to hold the unit level and direct condensate water out the back

• A proper sleeve helps meet energy efficiency standards — and avoid water leaks

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🔧 Step 3: DIY or Hire a Pro?

Here’s the truth:

• DIY install is doable if you’re comfortable cutting drywall, framing an opening, and sealing the sleeve. You’ll need a stud finder, level, reciprocating saw, caulking gun, and two steady hands.

• Professional install is 100% worth it if you're unsure. Expect to pay $200–$500 depending on wall type and wiring.

✨ Mavi Tip: If you live in a brick or masonry building, call a pro. That’s not a wall you want to DIY.

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🪜 Step 4: Prep Your Space

Before installation day:

• Move furniture and clear a 3–4 foot radius around the install area

• Have your AC, sleeve, and accessories on-site

• Check for exterior clearance (the unit will extend outside 8–14")

• Put down drop cloths to catch dust

• Take photos of the area for reference in case you need repairs later

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⏳ Step 5: How Long Will It Take?

Total time: ~3–5 hours for a pro; ~1 full day for a first-time DIYer.

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🧽 Step 6: Seal It Up Right

Once the unit is in:

• Use foam insulation or weatherstripping around the interior edge

• Apply outdoor-grade caulk on the exterior to seal against water and bugs

• Plug in the unit and let it rest for 1–2 hours before running (helps refrigerant settle)

Check your user manual for leveling instructions — a slight tilt toward the outside is usually best for drainage.

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🚩 Common Mistakes to Avoid

❌ Cutting through a load-bearing wall
❌ Forgetting to check electrical compatibility
❌ Installing without a sleeve
❌ Skipping the sealant (hello, bugs and drafts!)
❌ Using the wrong sleeve size (not all units are universal)

Still worried? Call the brand’s support team or check manufacturer videos. Some of my favorite ACs have great walkthroughs like this one from Perfect Aire.

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💬 Final Thoughts from Mavi

Installing a wall AC takes more effort up front, but the payoff is so worth it.
You’ll enjoy quiet cooling, better energy efficiency, and clean aesthetics — no clunky window views or janky brackets required.

And don’t forget — The Furnace Outlet has a full collection of wall ACs and sleeves that are built for real-life use, not just sales brochures.

Need help picking the right combo? Drop me a message. I love helping savvy shoppers get the comfort they actually paid for.

Until next time —
Stay cool, stay confident, and stay savvy.
— Mavi

In the next topic you will read about: How to Quiet a Noisy Wall AC (Without Breaking It)