Add a split-system air conditioner to Home Assistant without relying on a vendor cloud if the hardware allows it, then add one cautious automation (for example, switching the unit off when a window is open, or holding a modest setpoint). Read the companion introduction in this forum first so you know whether your brand is a local Daikin path, a Mitsubishi MELCloud path, or an ESPHome path.
Complexity
Moderate for a supported official integration or a well-documented ESPHome IR controller. Advanced if you are adding a CN105 interface inside an indoor unit. Mains and refrigeration work remains licensed trade work.
Option A — official local Daikin integration
If your Australian indoor unit uses a supported adapter from the Daikin AC documentation (for example BRP072A42 or a listed BRP072Cxx / Zena unit):
- Connect the official adapter as the manufacturer instructs, and join it to the same trusted LAN as Home Assistant. Give it a DHCP reservation.
- In Home Assistant: Settings, Devices & services, Add Integration, Daikin AC. Official docs say the integration can be auto-discovered.
- Confirm climate entities: mode, target temperature, fan and swing, as supported by your model.
- Do not expose the adapter's management port to the internet.
If the Mitsubishi unit only offers MELCloud or MELCloud Home, use the matching official integration — MELCloud or MELCloud Home — and treat internet outages as an expected limitation. Prefer a later local interface if the installer can offer a supported one.
Option C — ESPHome IR, as a local add-on
ESPHome IR Remote Climate can drive a compatible indoor unit from an ESP32 with an IR transmitter. Official platforms include daikin and mitsubishi (and several Daikin variants). A typical shape, from the official component docs, is a climate platform with a remote_transmitter. You will need a 5 V or 3.3 V IR LED circuit built for that purpose — not a random phone blaster.
Limitations to accept up front: the indoor unit may not report true state unless you also receive IR; someone using the original remote can desynchronise Home Assistant; line-of-sight and afternoon sun on the IR window both matter.
Option D — ESPHome Mitsubishi CN105, only with a proper interface
The official Mitsubishi CN105 climate component uses UART at 2400 baud and supports heat, cool, dry, fan-only and heat/cool on compatible units. This is the more complete local Mitsubishi path, but it is a connection on the indoor unit. Use a purpose-made isolated interface, follow the vendor's instructions, and ask the air-conditioning installer about warranty before you proceed. This project does not describe improvised wiring inside the unit.
A first, cautious automation
Once you have a climate entity, keep the first automation dull and safe:
- If a window or door sensor reports open for more than a few minutes, turn the climate entity off or to fan only.
- Or, hold a modest away setpoint rather than swinging between extremes.
Hardware cost
A manufacturer Wi-Fi adapter, an ESP32 IR interface, or a CN105 interface should be quoted or purchased from a documented supplier in AUD. Prices move, and compatibility matters more than a bargain module. No single public price is used here.
Official reading
Daikin AC
ESPHome IR climate
ESPHome Mitsubishi CN105
Researched from official documentation on 15 November 2026 (Australia/Sydney). This is a planning and how-to guide, not a claim that the exact hardware combination was assembled and tested on a live site. Please correct anything that has moved on.