Mini-splits are like magic in the world of air conditioning. They’re quiet, powerful, and don’t need ductwork. But here’s the strange thing: most people still operate them manually. With a remote. Like it’s 2005.
Now imagine this: you come home, and your ductless split system heat pump has already cooled the room to the perfect temperature. Why? Because it “knows” when you’re home. And that’s not sci-fi — it’s real with a microcontroller and an IR blaster.
Why automating your mini split is not a luxury but a necessity:
- Energy savings: smart control cuts down your bills.
- Comfort: the climate adapts to your schedule.
- Remote access: control the system from the Maldives if you want.
- Smart home integration: create scenes like “wake up – turn on heat.”
- Ecosystem support: works with Home Assistant, Node-RED, and more.
The Basics: How a mini split and its IR control work
Most mini splits, even advanced ductless split system heat pump units, are controlled via infrared (IR) signals — just like your old TV. A microcontroller can emulate this signal and effectively “press” remote buttons for you. The trick is training the device with the right codes and ensuring a stable signal.
Core components of IR control for a mini split:
- IR transmitter (typically 38 kHz)
- Microcontroller (e.g., ESP8266 or ESP32)
- Code library: IRremote, Tasmota, or built-in in Home Assistant
- Proper transmitter placement — it must “see” the air conditioner
Popular mini splits brands that support IR control:
- Mitsubishi Electric
- Daikin
- GREE
- LG
- Pioneer
- Bravo
- Olmo
- Cooper&Hunter
- Fujitsu
Tip: Even if your remote looks “analog,” in 90% of cases it transmits IR signals. Check this by pointing a smartphone camera at the remote — when pressing buttons, you’ll see blinking.
What you need to automate your mini split: List of components
To make your mini splits smart, you only need a few components and some enthusiasm. Everything revolves around the microcontroller and the IR transmitter. Essentially, you’re building an electronic “stand-in” for the remote, one that follows your rules, schedules, and logic from Home Assistant or other platforms.
You’ll need:
- Microcontroller: ESP8266 or ESP32 — compact, powerful, Wi-Fi capable. ESP32 is preferred if using more sensors.
- IR blaster (IR LED): standard 940nm IR LED + transistor to boost the signal. It will send commands to the air conditioner just like a regular remote.
- Power supply: stabilized 5V source, ideally via USB or a dedicated power adapter.
- Firmware: Tasmota, ESPHome, or even basic Arduino code. The choice depends on your platform (e.g., use ESPHome for Home Assistant).
- Enclosure: optional but helps with aesthetics and protection. A 3D-printed case can make the setup look like a mini router.
- Optional (but useful): temperature, humidity, and light sensors, IR receiver for learning remote commands.
Important: Place the IR blaster within the direct line of sight of the indoor unit of the ductless split system heat pump. Otherwise, the signal may not reach or be unstable.
How to Send IR Commands: Tasmota, ESPHome, Arduino, and Other Options
Sending IR commands is not magic — it’s precise engineering. Fortunately, the community has already done the heavy lifting. There are libraries and firmware options that know how to “speak” to specific mini-splits. Your task is choosing the right platform.
Option 1: Tasmota
Tasmota is prebuilt firmware that you can flash via a web interface. It supports sending IR commands via console or HTTP requests. Ideal if you want a quick setup without programming. Has built-in templates for popular brands.
Option 2: ESPHome
Perfect for Home Assistant users. Lets you write YAML configurations with commands like turn_on, set_temperature: 24°C, and mode: cool. A very flexible approach, easily expandable with automation logic (e.g., “if bedroom temperature >26°C — turn on cooling”).
Option 3: Arduino
For those who want full control. Use the IRremoteESP8266 library. It lets you both read commands from the remote and transmit them. A bit more complex, but ideal for custom setups, advanced logic, or integration with other systems.
Example logic: If the temperature sensor reads >27°C and someone is home — send a command to turn on the ductless split system heat pump in cooling mode at 24°C. If nobody’s home — don’t turn it on.
How to Build a Wi-Fi IR Blaster for Mini Splits: Step-by-Step Guide
Building your own mini split control system is easier than it sounds. The key is a clear plan and a few tools. Here’s what to do:
Gather components: ESP32 microcontroller, IR LED, resistors, transistor (e.g., 2N2222), power supply, and wires.
Assemble the circuit: connect the IR LED through the transistor to an ESP32 pin to boost the signal. Use a resistor to limit current and protect the LED.
Flash the firmware: we recommend ESPHome — just create a YAML config file and upload via USB.
Test IR signal transmission: you can use the A/C remote and an IR receiver on the ESP32 to “read” commands.
Configure integration with Home Assistant or another platform: connect the device to your Wi-Fi network, and set up automation.
Mount the IR blaster: aim it at the indoor unit of the ductless split system heat pump — without obstructions.
If something isn’t working, check your soldering and ensure the power supply is stable — this is where most DIY projects run into trouble.
Why Automating Mini Splits with a Microcontroller is Smart and Worth It
Sure, you could buy an expensive “smart” remote or a proprietary system. But the DIY approach with ESP32 and an IR blaster offers several unbeatable advantages:
- Cost savings: instead of spending hundreds on branded accessories — just $10–20 in parts.
- Flexibility: configure exactly the behavior you need, without extra features or pushy apps.
- Integration: your mini-splits become part of the smart home, enabling complex scenes — from schedules to weather-based reactions.
- Autonomy: once set up, no need to run for the remote — commands are sent automatically.
- Community support: thousands of enthusiasts and open-source solutions — you can always find help or improvements.
In the end, you don’t just get an air conditioner — you get an intelligent climate system that saves energy and makes life more comfortable.