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Installing the GE 12,000 BTU Wall AC with Heat: Can You DIY or Should You Call a Pro?

Installing a through-the-wall AC like the GE 12,000 BTU 208/230V AJEQ12DWJ isn’t rocket science—but it’s also not a “plug it in and forget it” situation like a window unit. The truth I give every homeowner is this:

**You absolutely can install this unit yourself.

But not everyone should.**

In my years of troubleshooting these systems, I’ve seen perfect DIY installs, and I’ve seen the kind of DIY disasters that cost more to fix than the AC itself—crooked sleeves, leaks inside the wall, electrical problems, mold from bad drainage, and units that burn out in two years instead of ten.

This guide cuts out the fluff and gives you the real homeowner’s breakdown of what it takes to install this GE wall AC the right way.
Not the manufacturer brochure version—
the version from a guy who has actually done it hundreds of times.

1. What Makes This GE Unit Different to Install?

The GE AJEQ12DWJ isn’t your average window unit with a flimsy frame and cheap plastic vents.

Here’s what you’re dealing with:

✔ It’s a 208/230-volt unit

This means:

You need a 208/230V outlet.
You may need an electrician.
You cannot run this on a standard 115V home circuit.

✔ It must be installed in a wall sleeve

Window units sit in the window.
This guy needs a 26-inch through-the-wall sleeve.

✔ It weighs more than a window AC

This thing is a tank—usually around 90–110 lbs.

✔ The sleeve must be pitched for drainage

Wrong pitch = water inside the home.
(Ask me how I know.)

✔ The room must be sized correctly

Too small? Unit will short-cycle.
Too big? It will run nonstop and wear out faster.

✔ The wall opening MUST be properly sealed

Drafts ruin efficiency and cause humidity problems.

Reference: Residential AC Installation Safety Standards

2. Can the Average Homeowner Do This Themselves?

Short answer?
Yes, absolutely—IF you have the right tools and confidence.

This install isn’t about brute force. It’s about:

accuracy
leveling
cutting a clean wall opening
sealing properly
following electrical rules
and installing a wall sleeve the right way

If you can:

cut drywall
operate a reciprocating saw
drill into wood
measure precisely
and follow safety steps

Then you can do this.

But if any of these make you nervous, calling a pro is worth it.

3. Tools You’ll Need for a Proper Installation

This is the list I bring to every install:

Cutting & Framing Tools

Reciprocating saw
Circular saw (optional for exterior siding)
Drywall saw
Oscillating multi-tool
Stud finder
Level (24" minimum)
Tape measure
Utility knife

Mounting & Sleeve Tools

Drill + screws
Shims
Backer rod
Spray foam rated for windows/doors
Exterior flashing tape
Caulk gun + exterior-grade caulk

Electrical Tools

Non-contact voltage tester
Screwdrivers
Wire staples (if running a new circuit)
Voltage meter (optional)

Reference: HVAC Electrical Code Compliance Guidelines

Helper Tools

Work gloves
Safety glasses
Drop cloth
A second person (trust me on this one)

If you don’t have 60% of these tools, hire a pro.

4. Step-by-Step Installation (Mike’s Field-Proven Method)

I’m giving you the exact method I use on real jobs—not the shortcuts, not the manufacturer’s overly simplified version, but the version that avoids callbacks.

Step 1: Choose the Right Location

The best spot:

An exterior wall
Centrally located
Not above outlets or wiring
At a comfortable height (~12–18" off the floor)
Clear of furniture blocking airflow

Avoid:

Corners
Behind door swings
Opposite tall bookshelves
Walls with plumbing

Reference: Through-the-Wall AC Structural Requirements

Step 2: Locate Studs and Electrical Lines

Use a stud finder.
Mark:

studs
wiring paths
plumbing

If the stud layout forces you to cut a load-bearing stud,
stop here and call a pro.

Step 3: Trace the Sleeve

Never freehand the wall opening.
Use the actual sleeve:

Remove the rear grille.
Hold the sleeve against the interior wall.
Level it.
Trace the outline exactly.

Pro tip:
Add ¼" clearance on all sides.

Step 4: Cut the Drywall Cleanly

Use an oscillating tool or drywall saw.

Cut only the drywall—not the exterior yet.

This lets you inspect:

framing
wiring
structural elements

Step 5: Cut the Exterior Wall

This step separates real DIYers from weekend warriors.

If your exterior is:

Vinyl → Easy
Wood siding → Moderate
Stucco → Tough
Brick → Hire a pro

Use a reciprocating saw.
Cut slow.
Stay on your line.

Step 6: Insert and Level the Wall Sleeve

This is the single most important part of the entire project.

✔ The sleeve MUST be level left-to-right

✔ The sleeve MUST pitch downward ¼" to the outside

This prevents rainwater and condensation from flowing back indoors.

Reference: Wall Sleeve Installation and Pitch Specifications

Shim as needed.

Step 7: Secure the Sleeve to the Wall

Use screws through the sleeve flanges, into structural studs or new support framing.

Never rely on drywall alone.

Step 8: Seal Around the Sleeve

This stops:

humidity
bugs
noise
drafts
heat intrusion

Use:

backer rod
spray foam
exterior caulk
flashing tape outdoors

Reference: Moisture and Drainage Control Best Practices

This step affects both comfort and efficiency long-term.

Step 9: Install the Rear Grille

Make sure it:

matches the airflow design
sits flush
doesn’t block exhaust

The GE unit pushes a lot of air.
A restrictive grille suffocates the compressor.

Step 10: Slide in the GE AJEQ12DWJ

This is where the second person helps.

The unit is heavy.
Do not try to muscle it in alone.

Slide slowly and make sure:

the rails engage
the gap is tight
the interior trim fits properly

Step 11: Plug In the 208/230V Circuit

If you don’t already have a 208/230V outlet:

Hire a licensed electrician
Do NOT adapt a 115V line
Do NOT install a 230V circuit without permits

Reference: HVAC Electrical Code Compliance Guidelines

Step 12: Test Cooling, Heating & Drainage

Turn on:

Cooling mode
Heating mode
Fan mode

Check:

vibration
noise
pitch
exterior drainage

A properly installed unit drains outdoors within 10–30 minutes of cooling operation.

5. When DIY Makes Sense (Mike’s Criteria)

DIY is great if you:

✔ Have carpentry experience
✔ Own most of the tools
✔ Are comfortable cutting exterior walls
✔ Have a helper
✔ Have good stud access

DIY saves $400–$1,200 in labor, depending on your region.

If you're confident, go for it. This is doable.

6. When You Should Call a Pro (Mike’s Honest Opinion)

You should absolutely hire a pro if:

❌ Your exterior wall is brick

❌ Your home is older than 1980 (unknown wiring)

❌ You hit unexpected wiring or plumbing

❌ You don’t have a 208/230V circuit

❌ The wall opening needs structural modification

❌ You’ve never used a reciprocating saw

❌ You're anxious about sealing and framing

The cost of fixing a bad install often exceeds hiring a pro upfront.

7. The Most Common DIY Mistakes I See (And How to Avoid Them)

These come from actual jobs I’ve repaired.

❌ Cutting between the wrong studs

Leads to structural issues.

❌ Forgetting the OUTWARD pitch

Causes indoor leaks and mold.

❌ No sealing around the sleeve

Creates drafts and noise.

❌ Using the wrong rear grille

Compressors overheat and die early.

❌ Insulating inside the sleeve

Airflow gets blocked.

❌ Crooked wall cuts

AC never sits right.

❌ Using a 115V outlet

The unit will not run. Ever.

8. Electrical Requirements Most Homeowners Don’t Expect

The GE AJEQ12DWJ is a 208/230V unit.

This means:

You need a double-pole breaker.
You need 12/2 or 10/2 wiring, depending on amperage.
You need a 208/230V receptacle.
You cannot convert a 115V circuit.
You must follow electrical code.

If this sounds confusing—hire an electrician.

9. How Long Does a Professional Installation Take?

A pro installer (with an electrician available) can do the job in:

2–3 hours if sleeve exists
4–6 hours if cutting new wall
6–8 hours for brick or stucco exterior

DIYers usually take:

1–2 days
Sometimes a full weekend

And that’s okay — you’re not doing this every day.

10. Cost Breakdown: DIY vs. Hiring a Pro

DIY Costs

Sleeve: $80–$150
Tools (if needed): $100–$300
Electrical outlet: $75–$200
Materials: $40–$80
Total: $300–$600

Professional Installation

Sleeve installation: $300–$700
Electrical: $250–$600
AC installation labor: $200–$500
Total: $750–$1,800

If you already have a sleeve and a 230V outlet, your professional cost drops dramatically.

11. Final Verdict: DIY or Pro? (Mike’s Recommendation)

Here’s my straight, no-sales-pressure verdict:

Go DIY if:

Your exterior wall is easy to cut
You’re handy with tools
You understand basic electrical safety
You already have a 230V outlet
You’ve done home projects before

Call a Pro if:

You’re working with brick or stucco
You don’t have a 230V circuit
You’re uncomfortable cutting exterior walls
You want a guaranteed pitch and seal
You want zero risk of leaks or mold

The GE AJEQ12DWJ is a great unit — but like any through-the-wall AC, it’s only as good as the installation behind it.

If you're confident, give it a shot.
If you’re not? This is one job where hiring a pro is worth every penny.

In the next blog, Mike will tell how this system handles winters.

Tags: Cooling it with mike

WRITTEN BY

Mike Sanders

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