[mitsubishi_cn105] Add climate component for Mitsubishi A/C units with CN105 connector by crnjan · Pull Request #14979 · esphome/esphome

crnjan · 2026-03-19T19:45:17Z

Description

Adds support for Mitsubishi A/C units using the CN105 connector.

It is an independent implementation of the protocol used in i.e. the SwiCago HeatPump project, developed from scratch, while supporting the same devices. The driver is designed to be non-blocking, with a focus on performance and reliability.

The initial version was originally developed for ESPEasy (PR) and has since been adapted and refactored for ESPHome.

Supported features (initial version)

Target temperature control
Current temperature reporting
HVAC modes (heat/cool/auto/dry/fan_only/off)
Fan modes:
- auto
- quiet
- low
- medium
- middle
- high

Notes

Communication is done over UART (CN105 connector).
Supported baud rates are 2400 or 9600, depending on the A/C unit.
This PR focuses on a minimal, stable feature set; some functionality (such as vane and wide vane control) has been intentionally omitted and may be added in follow-up PRs.
Mitsubishi units expose multiple intermediate fan speed levels. These are mapped to ESPHome fan modes, including both medium and middle, which represent distinct speeds.
The update interval determines how quickly the UI reflects external changes (e.g. when operating the unit via IR remote). It can be set as low as needed; the default is 1s. During testing, a 500ms update interval provided near-instant feedback and remained stable over several days.
While several community implementations and approaches for CN105 exist, ESPHome currently does not provide an official integration.

Testing

Tested on:

ESP8266

Types of changes

Bugfix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected) — policy
Developer breaking change (an API change that could break external components) — policy
Undocumented C++ API change (removal or change of undocumented public methods that lambda users may depend on) — policy
Code quality improvements to existing code or addition of tests
Other

Pull request in esphome-docs with documentation:

[mitsubishi_cn105] Add documentation for Mitsubishi CN105 climate component esphome-docs#6329

Test Environment

Example entry for `config.yaml`:

uart:
  id: ac_uart
  tx_pin: GPIO1
  rx_pin: GPIO3
  baud_rate: 2400
  parity: EVEN

climate:
  - platform: mitsubishi_cn105
    name: "Air Condition"
    uart_id: ac_uart
    update_interval: 1s

Checklist:

The code change is tested and works locally.
Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

Documentation added/updated in esphome-docs.

github-actions · 2026-03-19T19:45:27Z

To use the changes from this PR as an external component, add the following to your ESPHome configuration YAML file:

external_components:
  - source: github://pr#14979
    components: [mitsubishi_cn105]
    refresh: 1h

(Added by the PR bot)

esphome

📦 Pull Request Size

This PR is too large with 1202 line changes (excluding tests). Please consider breaking it down into smaller, focused PRs to make review easier and reduce the risk of conflicts.

For guidance on breaking down large PRs, see: https://developers.esphome.io/contributing/submitting-your-work/#how-to-approach-large-submissions

esphome · 2026-03-19T19:45:33Z

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

Learn more about our pull request process.

codecov-commenter · 2026-03-19T19:46:30Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.44%. Comparing base (a3913b9) to head (824f2d6).

Additional details and impacted files

@@           Coverage Diff           @@
##              dev   #14979   +/-   ##
=======================================
  Coverage   75.44%   75.44%           
=======================================
  Files          55       55           
  Lines       12166    12166           
  Branches     1683     1683           
=======================================
  Hits         9179     9179           
  Misses       2568     2568           
  Partials      419      419

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esphome

📦 Pull Request Size

This PR is too large with 1058 line changes (excluding tests). Please consider breaking it down into smaller, focused PRs to make review easier and reduce the risk of conflicts.

For guidance on breaking down large PRs, see: https://developers.esphome.io/contributing/submitting-your-work/#how-to-approach-large-submissions

Review dismissed: All requirements have been met

Copilot

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 4 comments.

esphome/components/mitsubishi_cn105/mitsubishi_cn105.cpp

crnjan · 2026-03-30T15:16:35Z

I’m splitting the PR into smaller chunks to simplify review — leaving this here for completeness. Also marked as draft so it’s not reviewed twice.

j9brown · 2026-03-30T15:57:10Z

Splitting it sounds like a good idea. I can imagine the first patch would just connect to the device and perform some basic enumeration of its capabilities, for example. And later patched can layer on the control functions.

nagyrobi · 2026-03-30T16:12:25Z

Place a link here to the new PR for the ones arriving here to know where to go

crnjan · 2026-03-31T07:07:29Z

The split PRs do not yet provide meaningful functionality, so for anyone who wants to test, please use this PR. I’ll share updates here as well.

esphome

📦 Pull Request Size

This PR is too large with 1006 line changes (excluding tests). Please consider breaking it down into smaller, focused PRs to make review easier and reduce the risk of conflicts.

For guidance on breaking down large PRs, see: https://developers.esphome.io/contributing/submitting-your-work/#how-to-approach-large-submissions

crnjan · 2026-03-31T09:25:07Z

@mdegat01 — I’ve added a use_fahrenheit_conversion option. Feel free to give it a try and let me know how it works for you. I don’t use Fahrenheit myself, so it hasn’t been tested in a real setup. Removing it or setting it to false should restore the previous behavior.

As always, testing bleeding-edge changes can occasionally lead to issues (e.g. I recently hit an infinite boot loop with VERY_VERBOSE logging), so a manual reflash might be needed in the worst case — which can be a bit annoying when the device is mounted inside the AC.

nagyrobi · 2026-04-05T08:10:29Z

With Part3 merged, is it all in? Or any more to submit?

crnjan · 2026-04-05T09:42:45Z

With Part3 merged, is it all in? Or any more to submit?

Part 3 includes reading of temp (room & current), part 4 will add mode and fan (read only) and part 5 set operations.

If anybody can confirm if use_fahrenheit_conversion works (included in this PR) I would include that as well in the "offical" PRs.

crnjan · 2026-04-06T20:09:41Z

Aside from use_fahrenheit_conversion, the current dev branch now contains the same functionality as this PR, so I’m closing it.

nagyrobi · 2026-04-07T13:22:02Z

Since this PR will soon be locked to comments as it was closed, here's a discussions topic as follow up: https://github.com/orgs/esphome/discussions/3609

Initial commit of mitsubishi_cn105 component

aca2095

esphome bot previously requested changes Mar 19, 2026

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esphome bot added has-tests needs-docs new-component new-feature new-platform too-big component: mitsubishi_cn105 labels Mar 19, 2026

esphome bot marked this pull request as draft March 19, 2026 19:45

crnjan added 3 commits March 19, 2026 21:39

fixed esphome bot requested changes

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fixed esphome bot requested changes

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fixed esphome bot requested changes

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crnjan marked this pull request as ready for review March 19, 2026 21:55

crnjan marked this pull request as draft March 20, 2026 07:14

Removed vane/vertical swing support in initial PR.

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crnjan added 2 commits March 20, 2026 08:51

Removed transport layer abstraction to simplify PR.

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Removed enum mappings for logging to reduce PR size

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esphome bot removed the too-big label Mar 20, 2026

crnjan changed the title ~~[mitsubishi_cp105] Add climate component for Mitsubishi A/C units with CN105 connector~~ [mitsubishi_cn105] Add climate component for Mitsubishi A/C units with CN105 connector Mar 20, 2026

crnjan mentioned this pull request Mar 20, 2026

[mitsubishi_cn105] Add documentation for Mitsubishi CN105 climate component esphome/esphome-docs#6313

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crnjan marked this pull request as ready for review March 20, 2026 16:41

esphome bot removed the needs-docs label Mar 20, 2026

Merge branch 'dev' into feature/mitsubishi_cn105

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Copilot started reviewing on behalf of crnjan March 29, 2026 18:30 View session

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crnjan added 5 commits March 29, 2026 21:23

Add unit tests for status update handling

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Merge branch 'dev' into feature/mitsubishi_cn105

d37d667

Avoid dereferencing the optional directly

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Avoid dereferencing the optional directly

87ffae1

Avoid dereferencing the optional directly

e16854b

crnjan marked this pull request as draft March 30, 2026 14:32

crnjan mentioned this pull request Mar 30, 2026

[mitsubishi_cn105] Add climate component for Mitsubishi A/C units with CN105 connector (Part 1) #15315

Merged

18 tasks

crnjan added 2 commits March 31, 2026 09:51

Merge branch 'dev' into feature/mitsubishi_cn105

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Add Fahrenheit adjustments

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esphome bot requested changes Mar 31, 2026

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esphome bot added the too-big label Mar 31, 2026

This was referenced Apr 1, 2026

[mitsubishi_cn105] Add climate component for Mitsubishi A/C units with CN105 connector (Part 2) #15358

Merged

[mitsubishi_cn105] Add climate component for Mitsubishi A/C units with CN105 connector (Part 3) #15437

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This was referenced Apr 5, 2026

[mitsubishi_cn105] Add climate component for Mitsubishi A/C units with CN105 connector (Part 4) #15462

Merged

[mitsubishi_cn105] Add climate component for Mitsubishi A/C units with CN105 connector (Part 5) #15483

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crnjan closed this Apr 6, 2026

esphome bot added the by-code-owner label Apr 7, 2026

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crnjan deleted the feature/mitsubishi_cn105 branch April 8, 2026 10:42

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Description

Supported features (initial version)

Notes

Testing

Types of changes

Test Environment

Example entry for config.yaml:

Checklist:

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crnjan commented Mar 19, 2026 •

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Example entry for `config.yaml`:

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