ESP32 AC Climate Controller for Home Assistant

An ESP32 AC climate controller is one of the best upgrades you can make to an ordinary infrared-controlled air conditioner. Instead of using the original remote control every time, you can let Home Assistant turn the AC on, change the temperature, switch between cooling and heating, and automate it based on room temperature, time of day, presence, window sensors or electricity prices.

The basic idea is simple:

The ESP32 sends infrared commands to the air conditioner
ESPHome exposes the AC as a Home Assistant climate entity
A temperature sensor reports the actual room temperature
Home Assistant automations decide when and how the AC should run

ESPHome has an IR Remote Climate component for compatible air conditioners. It works by sending infrared control signals in the same way as the original handheld remote. It requires a configured remote_transmitter component.

What this project does

This guide shows how to build an ESP32-based AC controller that can:

Control an infrared air conditioner from Home Assistant
Show the AC as a thermostat-style climate entity
Report the actual room temperature
Send cooling, heating, fan and temperature commands
Optionally track the original remote if your AC protocol supports an IR receiver
Work locally without cloud services or manufacturer apps

This is useful for:

Split air conditioners
Portable AC units
Heat pumps
Older ACs with only an IR remote
Guest rooms, bedrooms, offices and living rooms
Home Assistant energy-saving automations

Important limitation before you start

An ESP32 IR AC controller is not electrically connected to the air conditioner. It does not talk to the AC over Wi-Fi, UART or a manufacturer API. It simply sends infrared commands like the original remote.

That means the ESP32 usually assumes the AC state based on the last command it sent. ESPHome’s documentation explicitly notes that IR climate control is unidirectional, so the component cannot always know the real state of the AC unless receiver support is available for that protocol.

So if someone uses the original remote, Home Assistant may not know unless:

You also install an IR receiver
Your selected ESPHome climate platform supports receiver tracking
The AC protocol exposes enough state information

For most normal automations, this is still very usable.

Parts needed

Part	Notes
ESP32 development board	ESP32 DevKit, ESP32-S3 or similar
940nm IR LED	Used to transmit commands to the AC
NPN transistor or logic-level MOSFET	Strongly recommended for better IR range
Resistors	Usually 100–220Ω for IR LED, 1kΩ for transistor base
DS18B20 temperature sensor	Simple room temperature feedback
4.7kΩ resistor	Pull-up resistor for DS18B20 data line
Optional IR receiver module	Useful for learning or tracking remote codes
USB power supply	Keeps the controller permanently powered
Home Assistant with ESPHome	ESPHome add-on or ESPHome Device Builder

You can also use a better indoor sensor such as SHT31, SHT45 or BME280 instead of a DS18B20. For a basic build, the DS18B20 is cheap, easy and well supported by ESPHome. The ESPHome dallas_temp component supports DS18B20 and similar 1-Wire temperature sensors.

Recommended wiring

IR transmitter wiring

For very short range, some people connect an IR LED directly to an ESP32 GPIO through a resistor. That is not ideal.

For reliable AC control, use a transistor driver.

ESP32 / component	Connection
GPIO17	1kΩ resistor to transistor base
Transistor emitter	GND
Transistor collector	IR LED cathode
IR LED anode	5V through 100–220Ω resistor
ESP32 GND	Common GND with 5V supply

Place the IR LED so it points directly at the AC indoor unit’s IR receiver window.

DS18B20 wiring

DS18B20 wire/pin	ESP32
VCC	3.3V
GND	GND
DATA	GPIO4
4.7kΩ resistor	Between DATA and 3.3V

Do not place the temperature sensor directly next to the AC airflow. Put it somewhere that represents the actual room temperature.

Optional IR receiver wiring

IR receiver pin	ESP32
VCC	3.3V
GND	GND
OUT / DATA	GPIO23

The optional receiver is useful if you want the ESP32 to see commands from the original AC remote. ESPHome’s remote_receiver component can receive and decode common infrared and RF remote control signals.

Choose the right ESPHome AC platform

ESPHome supports several IR climate platforms, including Ballu, Coolix, Daikin, Delonghi, Fujitsu General, Gree, Hitachi, LG, Midea, Mitsubishi, Toshiba, Whirlpool, Whynter and others. Not all platforms support receiver tracking, so check your specific AC type before assuming the original remote will update Home Assistant.

Common examples:

AC brand / protocol	ESPHome platform
LG	`climate_ir_lg`
Midea / some Coolix units	`midea_ir`
Gree	`gree`
Daikin	`daikin`, `daikin_arc`, `daikin_brc`
Mitsubishi	`mitsubishi`
Toshiba	`toshiba`
Whirlpool	`whirlpool`
Many rebranded AC units	`zhlt01`, `coolix`, `midea_ir` or `heatpumpir`

If your AC is not supported, you can still use learned raw IR codes, but you may not get a proper thermostat-style climate entity. In that case, you can create buttons or scripts for common states such as “Cool 24°C”, “Heat 22°C” and “Off”.

Basic ESPHome YAML

This example uses:

ESP32
IR transmitter on GPIO17
DS18B20 temperature sensor on GPIO4
Midea IR climate platform as an example

Replace the climate platform with the one that matches your AC.

esphome:
  name: esp32-ac-controller
  friendly_name: ESP32 AC Controller

esp32:
  board: esp32dev

logger:

api:
  encryption:
    key: "PASTE_YOUR_API_KEY_HERE"

ota:
  - platform: esphome
    password: "PASTE_YOUR_OTA_PASSWORD_HERE"

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

  ap:
    ssid: "ESP32 AC Controller Fallback"
    password: "fallback-password"

captive_portal:

remote_transmitter:
  id: ir_transmitter
  pin: GPIO17
  carrier_duty_percent: 50%

one_wire:
  - platform: gpio
    pin: GPIO4
    id: one_wire_bus

sensor:
  - platform: dallas_temp
    name: "Living Room Temperature"
    id: room_temperature
    one_wire_id: one_wire_bus
    update_interval: 30s

climate:
  - platform: midea_ir
    name: "Living Room AC"
    sensor: room_temperature
    supports_cool: true
    supports_heat: true

After flashing, Home Assistant should discover a new climate entity called Living Room AC.

The room temperature shown in Home Assistant comes from the DS18B20 sensor. This does not replace the AC’s internal thermostat completely, but it gives Home Assistant a better view of the real room temperature.

Example for LG air conditioners

For LG units, try:

remote_transmitter:
  id: ir_transmitter
  pin: GPIO17
  carrier_duty_percent: 50%

climate:
  - platform: climate_ir_lg
    name: "Bedroom AC"
    sensor: room_temperature
    supports_cool: true
    supports_heat: true

ESPHome’s LG IR climate platform also has optional timing settings for some variants, so if your LG unit does not respond correctly, check the ESPHome LG climate options.

Example for Gree air conditioners

For Gree units:

remote_transmitter:
  id: ir_transmitter
  pin: GPIO17
  carrier_duty_percent: 50%

climate:
  - platform: gree
    name: "Office AC"
    id: office_ac
    sensor: room_temperature
    model: yan
    supports_cool: true
    supports_heat: true

Gree has different model/protocol options in ESPHome, including generic, yan, yaa, yac, yac1fb9, yx1ff and yag. Try the model that matches your remote behaviour.

Example for Mitsubishi air conditioners

For Mitsubishi units:

remote_transmitter:
  id: ir_transmitter
  pin: GPIO17
  carrier_duty_percent: 50%

climate:
  - platform: mitsubishi
    name: "Bedroom Heat Pump"
    sensor: room_temperature
    supports_cool: true
    supports_heat: true
    supports_dry: true
    supports_fan_only: true
    set_fan_mode: "quiet_4levels"

ESPHome’s Mitsubishi platform has options for fan modes, dry mode, fan-only mode and default vane direction. Some cooling-only Mitsubishi units may need supports_heat: false if the off command does not work correctly.

Adding an IR receiver

If your selected climate platform supports receiver tracking, you can add an IR receiver. This allows the ESP32 to detect when someone uses the original remote and update the climate state in Home Assistant.

Example:

remote_receiver:
  id: ir_receiver
  pin:
    number: GPIO23
    inverted: true
    mode:
      input: true
      pullup: true
  dump: all
  tolerance: 25%
  filter: 50us
  idle: 10ms

climate:
  - platform: midea_ir
    name: "Living Room AC"
    sensor: room_temperature
    receiver_id: ir_receiver
    supports_cool: true
    supports_heat: true

This is especially useful in family homes where some people still use the original remote.

Why AC remotes are different from TV remotes

A TV remote usually sends simple commands:

Power
Volume up
Volume down
Mute
Input

An AC remote is different. It often sends the full AC state every time:

Power on/off
Mode
Temperature
Fan speed
Swing position
Turbo mode
Sleep mode
Dry mode
Timer state

That is why learning one “temperature up” code is often not enough. The remote may actually send something like:

Cool mode, 23°C, auto fan, swing off, power on

This is also why ESPHome’s native IR climate platforms are better than raw button replay when your AC is supported.

Home Assistant automation examples

Once the AC appears as a climate entity, you can automate it like any other thermostat.

Turn on cooling when the room gets hot

alias: Turn on AC when living room is hot
trigger:
  - platform: numeric_state
    entity_id: sensor.living_room_temperature
    above: 27
condition:
  - condition: state
    entity_id: binary_sensor.living_room_presence
    state: "on"
action:
  - service: climate.set_hvac_mode
    target:
      entity_id: climate.living_room_ac
    data:
      hvac_mode: cool

  - service: climate.set_temperature
    target:
      entity_id: climate.living_room_ac
    data:
      temperature: 24
mode: single

Turn off AC when a window is open

alias: Turn off AC when window is open
trigger:
  - platform: state
    entity_id: binary_sensor.living_room_window
    to: "on"
    for:
      minutes: 2
action:
  - service: climate.turn_off
    target:
      entity_id: climate.living_room_ac
mode: single

Night cooling mode

alias: Bedroom AC night mode
trigger:
  - platform: time
    at: "23:30:00"
condition:
  - condition: state
    entity_id: binary_sensor.bedroom_presence
    state: "on"
action:
  - service: climate.set_hvac_mode
    target:
      entity_id: climate.bedroom_ac
    data:
      hvac_mode: cool

  - service: climate.set_temperature
    target:
      entity_id: climate.bedroom_ac
    data:
      temperature: 25
mode: single

Raw IR fallback method

If your AC is not supported by ESPHome’s IR climate platforms, you can still capture and replay raw IR commands.

The workflow is:

Use an ESP32 IR receiver to capture the original remote
Save useful states such as Cool 24°C, Heat 22°C and Off
Use remote_transmitter.transmit_raw or protocol-specific transmit actions
Expose each command as a Home Assistant button

ESPHome’s remote_transmitter supports protocol-specific actions such as LG, NEC, Midea, Samsung, Sony, Toshiba AC and raw IR transmission.

Example raw command button:

button:
  - platform: template
    name: "AC Cool 24"
    on_press:
      - remote_transmitter.transmit_raw:
          carrier_frequency: 38kHz
          code: [9000, -4500, 560, -560, 560, -1690, 560, -560]

The raw code above is only an example. You must replace it with the code captured from your own remote.

For ACs, create several fixed-state buttons:

Button	Captured state
AC Off	Power off
AC Cool 24	Cool mode, 24°C, auto fan
AC Cool 25	Cool mode, 25°C, auto fan
AC Heat 22	Heat mode, 22°C, auto fan
AC Dry Mode	Dry mode
AC Fan Only	Fan mode

This is not as elegant as a real climate entity, but it can still work very well for simple automations.

Placement tips

IR control depends heavily on placement.

For best reliability:

Point the IR LED directly at the AC receiver window
Keep the controller in line of sight
Use a transistor driver for stronger IR output
Avoid hiding the ESP32 inside a cabinet
Test from the final mounting position before sticking it to the wall
Use two IR LEDs at slightly different angles if the AC receiver is difficult to hit

A weak IR LED is the most common reason this project feels unreliable.

Troubleshooting

The AC does not respond

Check:

IR LED polarity
Transistor wiring
Common GND between ESP32 and LED power supply
Correct GPIO in remote_transmitter
IR LED pointing direction
Whether the AC protocol/platform is correct
Whether the AC uses a different variant of the same brand protocol

Use a phone camera to check if the IR LED is flashing. Many phone cameras can see infrared light as a faint purple/white flash.

Home Assistant shows the wrong AC state

This is normal if someone used the original remote and you do not have receiver tracking. IR is usually one-way. Home Assistant knows what it last requested, not necessarily what the AC actually did. ESPHome documents this assumed-state limitation for IR climate control.

Solutions:

Add an IR receiver if supported
Stop using the original remote
Use automations that periodically force the desired state
Use a smart plug power sensor to detect whether the AC is actually running

Temperature is inaccurate

Do not mount the sensor:

Directly under the AC airflow
Inside the ESP32 enclosure
Next to a window
Near sunlight
Near the ceiling

A DS18B20 inside a small plastic box with the ESP32 can read too warm because of board heat. Use a short cable and place the sensor outside the enclosure.

Heating mode does not work

Some ACs are cooling-only. Some ESPHome platforms also need options adjusted depending on model. For example, ESPHome notes that some Mitsubishi cooling-only units may need supports_heat: false to resolve off-command issues.

The AC beeps but does not change state

This usually means the IR command is close but not fully correct. Possible causes:

Wrong protocol variant
Wrong model option
Weak IR transmission
Raw code captured badly
AC expects a longer state packet
Carrier frequency or timing mismatch

Try moving the IR LED closer first. If that helps, the problem is probably transmission strength, not YAML.

Best automations for an ESP32 AC controller

Good automations include:

Turn off AC when windows or balcony doors are open
Pre-cool a room before bedtime
Run AC only when presence is detected
Disable cooling when electricity price is high
Turn off AC when everyone leaves home
Keep bedroom temperature between 24–26°C overnight
Use dry mode when humidity is high
Turn off AC if outdoor temperature is lower than indoor temperature

The big advantage is not just remote control from your phone. The real value is letting Home Assistant make better decisions than a basic IR remote.

Is this better than Sensibo, Tado or BroadLink?

It depends.

An ESP32 AC controller is better if you want:

Local control
No cloud account
Cheap hardware
Full ESPHome integration
Custom sensors and automations
A project you can repair or modify

A commercial IR controller may be better if you want:

No soldering
A polished app
Easier brand detection
Better enclosure
Less setup work

For an ESP32/Home Assistant setup, the DIY version is often more flexible and much cheaper.

Conclusion

An ESP32 AC climate controller turns a normal infrared air conditioner into a Home Assistant-controlled climate device. With ESPHome, an IR LED and a room temperature sensor, you can control cooling, heating and fan settings locally without relying on the AC manufacturer’s cloud service.

The best setup is:

ESP32 with IR transmitter
DS18B20, SHT31, SHT45 or BME280 room sensor
Optional IR receiver for original remote tracking
Native ESPHome IR climate platform where supported
Raw IR fallback only when the AC is not supported

For most homes, this is a very practical upgrade. It keeps the original air conditioner, keeps control local, and makes the AC part of your wider Home Assistant automation system.