Through-the-Wall Air Conditioners: How They Work in 2026

Through-the-wall air conditioners are a permanent cooling solution designed for rooms where window installation isn’t possible or practical. 

In this guide, we’ll explain how through-the-wall air conditioners work, how they compare to ductless mini-split systems, and, most importantly, how a smart controller like Klima can modernize and optimize wall AC performance.

What Is a Through-the-Wall Air Conditioner?

A through-the-wall air conditioner is a self-contained AC unit installed directly through an exterior wall. 

Unlike window units, it doesn’t block natural light. Unlike mini-splits, all components—compressor, condenser, and evaporator—are housed in one chassis.

These units are commonly used in:

• Apartments and rental properties

• Hotels and multi-family buildings

• Older homes without ductwork

• Rooms where windows are inaccessible

How Do Through-the-Wall Air Conditioners Work?

Through-the-wall ACs use a standard refrigeration cycle:

1. Warm indoor air is pulled into the unit

2. Refrigerant absorbs heat via the evaporator coil

3. Heat is expelled outdoors through the condenser

4. Cooled air is blown back into the room

Through-the-Wall AC vs. Mini-Split Systems

While through-the-wall ACs are convenient, ductless mini-split systems offer significantly better efficiency, comfort, and flexibility.

Mini-Split Basics

A mini-split system consists of:

• An outdoor unit housing the compressor

• One or more indoor air handlers

Refrigerant lines connect the two through a small wall opening—no ductwork required.

Because mini-splits deliver air directly into the room, they avoid the 25–30% energy loss caused by duct leakage, according to the U.S. Department of Energy.

Why Mini-Splits Are Replacing Wall Air Conditioners

1. Higher Efficiency

Mini-splits commonly achieve 20–30+ SEER2, compared to much lower ratings for wall ACs.

2. Heating and Cooling in One System

Most mini-splits are heat pumps, providing year-round comfort.

3. Quieter Operation

The compressor is outdoors, making indoor units dramatically quieter.

4. Zoned Comfort

Each room operates independently—no wasted energy.

Despite these benefits, mini-splits and wall ACs share one major weakness:

Their controls are outdated.

Klima - The Best Smart Thermostat for Through-the-Wall Air Conditioners

The Klima Smart Thermostat is purpose-built for all ductless air conditioners, including:

• Through-the-wall AC units

• Mini-split systems

• Window air conditioners

• Portable ACs

If your ductless air conditioner uses a remote with a display, Klima can control it.

How Klima Works With Wall Air Conditioners

Klima uses advanced IR remote emulation to precisely replicate your air conditioner’s native commands. Unlike generic controllers, it doesn’t rely on guesswork or presets—it mirrors the exact behavior of your unit.

Once connected to Wi-Fi, Klima replaces your basic remote with:

• App-based control

• Smart automation

• Energy intelligence

• Physical on-device controls

No rewiring. No HVAC technician. Setup takes under three minutes.

Key Features That Make Klima Ideal for Wall ACs

1. Universal Compatibility

Klima works with all major wall and ductless AC brands, including:
Mitsubishi, Daikin, LG, Fujitsu, Panasonic, Toshiba, and more.

2. Real Energy Monitoring & Cost Forecasting

Most wall ACs give you no insight into energy usage. Klima changes that with:

• Real-time usage tracking

• Cost estimates

• Efficiency insights to reduce waste

This is especially valuable for apartments, rentals, and multi-unit properties.

Klima - Smart Home Thermostat for Mini-splits, Air Conditioners and Heatpumps

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3. Built-In Environmental Sensors

Klima continuously tracks:

• Room temperature

• Humidity levels

• System behavior

This allows more accurate comfort control than a handheld remote ever could.

4. Smart Automation & Scheduling

With Klima, wall ACs gain:

• Daily and weekly schedules

• Geofencing (turns AC on/off based on your location)

• Voice control via Alexa, Google Assistant,Google Home, SmartThings, Apple Home and HomeKit

5. Physical Controls & Premium Design

Unlike app-only competitors, Klima includes:

• Touch controls

• On-device display

• Premium aluminum and glass construction

6. No Subscription Fees

All Boldr features are included permanently. No locked features. No monthly costs.

Why Klima Is Especially Useful for Through-the-Wall AC Owners

Through-the-wall air conditioners are often:

• Older

• Less efficient

• Installed in rentals or multi-family buildings

• Controlled by outdated remotes

Klima extends their lifespan and usability by:

• Improving efficiency through smarter scheduling

• Reducing unnecessary runtime

• Adding remote access for landlords and property managers

• Making legacy systems feel modern

Instead of replacing a working wall AC, Klima lets you upgrade the experience without replacing the hardware.

Final Thoughts

Through-the-wall air conditioners still serve a purpose—but their biggest weakness isn’t cooling power. It’s control.

Whether you’re using a wall AC today or planning to upgrade to a mini-split, the Klima Smart Thermostat bridges the gap between traditional hardware and modern expectations.

For homeowners, renters, and property managers looking to reduce energy use, improve comfort, and gain true smart control, Klima is the smartest upgrade you can make to a wall air conditioner.