Update 11.09.2026
This is the new overview of my Mitsubishi + Home Assistant external room-temperature project. The four approaches are separated below so the older offset methods and the recommended Remote Temperature setup are easy to distinguish.
1. Home Assistant simulates AUTO and chooses HEAT or COOL
Home Assistant uses one or more external room sensors and decides whether the Mitsubishi should run in HEAT or COOL. This is the legacy/fallback approach when native Mitsubishi AUTO is unsuitable for the installation.
Examples: living_room_multi_sensor.yaml and bedroom_single_sensor.yaml in the repository.
2. MELCloud Home + native Mitsubishi AUTO + offset/step compensation
AUTO stays AUTO, HEAT stays HEAT, COOL stays COOL. Home Assistant compensates the Mitsubishi target temperature using the external room temperature and the desired room temperature. Mitsubishi retains control of the operating mode. This path remains available for cloud-primary MELCloud Home installations.
Example: melcloud_home_external_temperature_control_public.yaml.
3. Local pymitsubishi + native AUTO + offset/step compensation
Control runs locally through the Mitsubishi adapter. Native AUTO is preserved, while Home Assistant uses the older target-offset method, including fixed 0.5 °C steps:
External room temperature → room error → offset/step correction → compensated Mitsubishi target.
This remains the local fallback if Remote Temperature is unavailable or unreliable.
4. Local pymitsubishi + Remote Temperature — recommended, without offset
With the local pymitsubishi/homeassistant-mitsubishi integration, the external room temperature is sent directly to the Mitsubishi as its Remote Temperature reference. The climate target is the real desired room temperature; the unit can use its own inverter/native AUTO logic.
When this works correctly with your adapter/unit, the old main-unit offset/step automation is no longer needed.
Setup
- Open the Mitsubishi Air Conditioner integration entry and reconfigure it.
- Enable Experimental Features.
- Select your External Temperature Sensor.
- Reload the integration if necessary.
- Open Temperature Source and change Internal to Remote.
- Verify that Remote remains selected after a Home Assistant restart.
- Set the real desired room temperature as the climate target.
- Disable the old main-unit offset/step automation for this unit.
One sensor or several sensors
Use a real room sensor, or combine several room sensors with an arithmetic-mean helper in Home Assistant and select that as the source. Independent room sensors are preferable to radiator-thermostat readings, which can be biased by their placement.
Fallback behavior
If the external sensor becomes invalid while Home Assistant is running, the integration can fall back to the internal sensor. If Home Assistant itself or the connection to the AC is lost while Remote is active, the unit may continue using the last received Remote Temperature until communication returns. Test this behavior on your installation.
What remains useful
Remote Temperature replaces the main AC temperature-compensation engine. Local control, MELCloud Home as a manual/fallback path, hvac_action, auxiliary-heating logic, winter reserve, away/vacation shutdowns, desired-temperature helpers, sensor averaging, vane control and restart-safe timers can still be useful.
Back up Home Assistant before changing the setup. Do not run two complete main controllers against the same physical unit simultaneously.
Documentation
GitHub: overview of all four paths
Recommended Remote Temperature guide
Feedback is welcome, especially with your adapter/unit model, integration version, selected path and observed AUTO/Remote Temperature behavior. Please omit credentials and private network details.