Im using this (https://www.amazon.com/gp/product/B081PX9YFV/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 D1Mini board from Amazon. It’s connected to my Ubiquity home network. The board is tucked into the floor of the plastic enclosure and has never dropped offline. I would look closely at where the board sits in your AC unit, add wifi data to your configuration or possibly consider upgrading your router. I can’t say enough good stuff about Ubiquity. I have several AP’s and absolutely no dead spots anywhere in the house and excellent signal when outside. Its 100% worth the investment!
Thanks for the tips.
I decided it must be down to a setting in my router that was causing the units to frequently disconnect, so I got to tinkering and achived some success.
On my TP-Link Archer AX1800 router, I had to:
- Disable the 5 GHz network (along with the Smart Connect feature). (Just disabling SmartConnect didn’t work.)
- Switch the 2.4 GHz network to mixed a/g/n, not a/g/n/ax.
- Disable OneMesh
- Disable IGMP proxy and snooping.
I tested combinations of these, but I needed to do at least the first three things to reliably stay on the network. I didn’t test whether it would still work if I re-enabled IGMP proxy and snooping. But with the current setup, my ESP8266’s often need me to connect to their own AP after a reboot and reboot them again, but then once they get on my WiFi, they stay there. This is if they’re powered by USB. I hope if someone else runs into the trouble I had, their search of the terms “ESP8266” and “TP-Link Archer AX1800” get them to this post. It would have saved me days of trial and error.
But even with a good reliable WiFi connection when powered by USB, once I connect these to my air handler (MSZ-GL18NA), they become unreliable again. I’ve confirmed 5V coming to the board, but they won’t stay on the WiFi. Usually, they need a reboot after I first install them, but then if they somehow do connect and fully communicate with HA, it lasts a few minutes before they’ll drop and go back to their own access point. The WiFi signal is strong (reporting at -52 dBm, and for testing, it’s dangling outside the air handler, so no interference). Sometimes, I’ll lose HVAC connection. I’m just about out of guesses here. I’ll take any advice for things to try at this point. Could my soldering be that bad, that they kinda work?
tl:dr: Boards work fine if powered by USB but won’t stay on my WiFi network and sometimes disconnect from the air handler when I connect them.
I’m brand new to HA and ESPHome (honestly coding in general), but wanted to make (2) of my Mitsubishi mini-split systems work remotely with an ESP8266 using ESPHome. I’ve been able to get the units running and connected to HA using the Geoff Davis github repo, but I’ve got MSZ units so I’d like to be able to use the vane option to move, however there’s only 2 options currently (vertical and horizontal).
I know the MQTT repo from Gysmo38 has the vane options working, so I was wondering if anyone has been able to get it to work using ESPHome?
I decided to try ESP01S boards before giving up on this, and it’s working! I needed to use ESP01S boards with 5V-3.3V adapter boards, so together they’re bigger than the ESP8266 were, but my first one is set in the air handler and has been reliable since installation a few days ago. I did need to retain all of the network-weakening router settings outlined in my prior post, but I’m OK with that. I guess the ESP8266 boards weren’t happy with the power supplied from the unit. My next boards should arrive tomorrow, and then I’ll get them installed around the house.
Do you have links to what you ended up using? I’m new to this and looking to give this a whirl. I was about to purchase the D1 minis (knowing that one might need to take a screw driver and sever some connection) but rather purchase the appropriate supplies that make this easy from the start.
Hi guys,
just wanted to chime in if anybody stumbles across this thread searching for information or a solution for EU Mitsubishi A/C units - if you DON’T have a CN105 connector on the mainboard!!!
My model is MSZ-HJ35VA (this also works for other MSZ-HJ models).
Using D1 mini for communication.
So the main-board in my A/C unit did not have a CN105 connector, I took some pins and soldered them in. When D1 is connected it gets powered on and connected to WiFi but HVAC status is DISCONNECTED. So I took the main-board out and started testing the traces from CN105 to the main processor - there is no connection between these two, and that’s the problem. I found the processor datasheet and identified the pins that are needed (RxD - pin42 and TxD - pin43) and noticed there are two empty SMD pads by the connector, and the processor pins are connected to them. So we are missing two resistors that connect the processor and CN105.
After some tinkering I found the right values and made some “test” resistors (didn’t have an SMD so used some normal connected in series to get the needed value) and BOOM it freaking works!!!
Here are the pics of the mod you need to do to get it working, hope it helps somebody:
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@kartcon I just purchased those boards as I plan to do this for my systems. Did you have to make a cut between the TX & RX as posted with an [amazon review](Amazon.com?
Hi @juan11perez
I am struggling to get my esp32 board to work using cn105 cable. You mentioned to got it so can you support me a bit?
I have connected the cable to 5v, gnd, tx,rd only without any resistor in the middle.
How do you have it connected and what esphome code are you using?
Thank you,
I have mitsubishi kirigamine zen unit and following this connections I got no success so far
- Esp32 + pap-04v-s connector (compatible with cn105)
from pap-04v-s to esp32
- 5v - 5v in esp32
- gnd - gnd in esp32
- tx - rx in esp32
- rx - tx in esp32
- 12v - no connected
Note: no resistor neither conversion to 3.3v
The only way I could connect to the esp32 over web server or home assistant was commenting “hardware_uart: UART1” in the climate section and although I can change values in the climate, it does not reflect to the Mitsubishi unit
I also tried with tx-tx and rx-rx, and also connecting to the esp32 gpio17 (tx2) and gpio16 (rx2) without response (access to the esp32).
Has anyone successfully got Mitsubishi unit connected using an esp32?
Thank you,
@miriumar
I’ll share a web article i found about 1 year ago which walks you step by step using tasmota on either an esp32 or 8266.
I have implemented with both boards and it works really well. Since using tasmota i’ve had practically zero issues.
I wanted to share the web link, but it seems it’s been removed since then:
https://isaiahchia.com/2022/06/16/integrating-mitsubishi-air-con-hvac-with-home-assistant-via-nodemcutasmota/
However, I saved a pdf of the artlcle and can share it with you. See below link
One issue I had with the esp32 ooard, was that one of the board types (34pin i think) has 2 x rx and 2 x tx pins and not both work. So if that’s your case, you’ll need to try both.
So you are not using esphlme but tasmota right? A pitty in my case because I am aiming to have everything in esphome because of easier maintenance.
And also you are using mqtt as you mentioned. Would like to have direct connectivity without mqtt but if no other way I will do. Nothing against mqtt but it is another layer to add between home assistant and the esp…
By the way, link you shared is up and working.
Thank you,
The reason I moved to tasmota is because when you update tasmota it updates to latest swicago library which is in continuous development.
The esphome swicago integration is not being actively maintained
Thanks for reply @juan11perez
Today, finally I get it working without need to MQTT just by setting up the esp32 to use UART1 with GPIOs 9 and 10 for RX and TX. I was unable to make it to work with UART0 neither UART2.
5V and GND remained as it was before.
Bit of newbie… but after compiling the firmware 15-20 times you end up crazy to figure out what worked vs not 
I will continue with esphome since checking the latest changes from swicago are not much longer than esphome. Indeed esphome one relies in the swicago library (specific version) but I could change this in the future if stops working.
Worst case scenario I could always try tasmota + mqtt if don’t work.
Thank you 
1 Like
Hi Skip! I wanted to add my wiring diagram for the Original WeMos D1 Mini. I was able to get four units up and running yesterday with the help of this thread but I didn’t see anyone specifically showing the wiring on this unit.
I used these chips, available on Amazon and Ali Express:
I set up my wiring using your photo as a guide. The wiring looks like this, this is showing the underside:
I followed this guide for my ESPHome setup: GitHub - geoffdavis/esphome-mitsubishiheatpump: ESPHome Climate Component for Mitsubishi Heatpumps using direct serial connection it also includes a link to the wiring for this model. I found this wiring diagram helpful
I originally purchased the wrong chips because I didn’t understand the difference. The others might have worked, as people on this thread have said, but I found it easier to purchase the correct chips.
Thanks, everyone for your input on this thread, it is so nice to have these all setup now! It only took about 3 hours for 4 units!
6 Likes
I followed this…
and works perfect for me and a friend of mine.
It is in Italian, but easy to translate in internet 
Hey, can you share the yaml for that card, i just cant work it out.
hi, I don’t know how to compile firmware. Do I only need to download the bin from that website and load it on a 8266?
It’s not quite that simple, unless there is a BIN file now available. Last I checked on the code, you had to download the code then compile it in the Arduino IDE to load it to the ESP8286 or similar chip.
To utilise this project, you will need to be comfortable with compiling firmware ,updating firmware regularly and tinkering in general with electrical and electronics . The firmware will need regular updates, especially when changes happen in Home Assistant, to keep it working.
As an example, I used the original code and library for the MSZ systems 5 years ago, and it was brilliant. If I used that identical code now, it would not work at all, and likely break Home Assistant if I tried to pull it in via MQTT.
Additionally, you do need to make sure that your ESP8286 is a good quality build and that your wiring is 100% correct. This little unit connects hardwired to the airconditioner, using the physical connector the Mitsubishi WiFi unit would use. If you cheap out on the ESP8286 development board, or you mess up your wiring, you could brick your air conditioner.
If I was doing this again now, I would actually make a little header board with fusing and protection on it, then mount the ESP8286 to that board instead of connecting the ESP8286 directly to an air-conditioning unit that costs hundreds, to over a thousand, dollars.
I just don’t trust a cheap $5 ESP8286 that much.