User Guide

This guide takes you from a Hisense A/C with an AEH-W41H1 Wi-Fi module to a climate device in Home Assistant that works without the ConnectLife cloud. Start here: this page helps you choose the hardware, says what state each choice is in, and names the page to read next.

There is one firmware, the hisense_ac ESPHome component. It talks to the A/C over the 4-pin RS-485 port the Wi-Fi module plugs into, and to Home Assistant over the ESPHome native API. What you choose is the board it runs on.

Not sure the unit is the right kind? See Will this work on my A/C?

Choose the hardware

  ESP32 replacement board The stock module Another ESPHome chip
What it is an ESP32-C3 SuperMini or a classic ESP32 with a 3.3 V RS-485 transceiver, plugged in where the module was the module that came with the A/C (Realtek RTL8710C), running ESPHome through the LibreTiny platform an ESP8266 D1 mini or a Raspberry Pi Pico W with the same transceiver
You add about 5 EUR of parts and four soldered wires nothing parts you already have
First flash USB cable over the air from this project’s retired Matter firmware (done once). From the vendor firmware it needs a SOIC-8 clip or UART download mode, and that has not been done USB cable
If an update goes wrong the bootloader rolls back to the previous image. A USB flash always recovers the board no rollback. An image that does not boot needs the clip and a dump of that unit taken beforehand USB flash
State today on live units since 2026-08, both boards the factory flash layout runs on one module in an A/C since 2026-10-10. The other two layouts compile and have never run. A second converted module went silent on the bus, cause unknown example configs that compile every night. Never run on a board
Read next ESP32 Replacement Board The Stock Module ESPHome Firmware

Use an ESP32 board unless you have a reason to keep the original module. The measured comparison is firmware/docs/13-path-comparison.md.

The route with an ESP32 board

  1. Look at the module and the port it plugs into: Hardware and Wiring.
  2. Build the board, and read the pins to avoid before you solder: ESP32 Replacement Board.
  3. Install ESPHome and fill in the secrets file: Build Environment.

  4. Flash it over USB. From firmware/esphome/:

    esphome run w41h1-esp32c3.yaml      # ESP32-C3 SuperMini
esphome run w41h1.yaml              # classic ESP32

    Or let the wrapper script ask before each step: python3 firmware/scripts/dev.py walk esphome --board c3. Its commands are in Build, Flash and Test.

  5. Bring it up in three stages: on the bench against the simulator, on the real bus with only A and B connected, then powered from the A/C (staged bring-up).
  6. Add the node to Home Assistant: ESPHome Firmware.
  7. Use it: Everyday Control.

The route with the stock module

Read The Stock Module and its risk list first. Take a full dump of the flash chip with the clip before anything else (Recovery and Reflash). The rest of the route (secrets, Home Assistant, everyday use) is the same as above.

When something breaks

Situation Page
A symptom you can name (no bus link, a command that does not take, a node Home Assistant cannot find) Troubleshooting and FAQ
What an entity or a counter means Entities and Diagnostics
The node has to move to another Wi-Fi network Wi-Fi Setup Mode and the Status LED
A board or a module that no longer answers Recovery and Reflash

What has not run on hardware

The firmware drives live A/Cs every day. These parts of the tree are host-tested or compile, and nobody has seen them work on a unit yet:

  • Wi-Fi setup mode and the remote’s “77” gesture (details).
  • The status pixel of the ESP32-C3 SuperMini Plus.
  • The stock module’s sdk and native flash layouts.
  • A first install of ESPHome on a stock module with the clip, and the clip tool that writes one firmware slot.
  • The ESP8266 and RP2040 example configs.

Each page repeats the note where it matters.

Other things to know

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