I have done exactly this with my own ducted Fujitsu system. I initially used the IRMQTTServer project from the IRremoteESP8266 library, which integrates into HA

I have done exactly this with my own ducted Fujitsu system. I initially used the IRMQTTServer project from the IRremoteESP8266 library, which integrates into HA through MQTT. https://github.com/crankyoldgit/IRremoteESP8266/blob/master/examples/IRMQTTServer/IRMQTTServer.ino https://github.com/crankyoldgit/IRremoteESP8266/blob/master/... I now use esphome on absolutely everything and it's WAY better, and I was able to eliminate MQTT from my stack. I could have used the built in climate component—it worked 99% perfectly. But in order to make the Fujitsu climate component behave consistently with the air conditioner itself (e.g. setting "dry" mode forces "auto" fan speed) I re-implemented the climate component as a custom component. https://gist.github.com/sjwright/8591ebd36b53bbed588179135c26b2d7 https://gist.github.com/sjwright/8591ebd36b53bbed588179135c2... I have three zones, so I took three "D1 Mini" style ESP8266 clones, attached an IR emitter to D5/GPIO14 and embedded it inside the air conditioner itself. Each AC has a little daughter board for status LEDs and the IR receiver; there's also 12 volts going to that which I use to power the D1 Mini, which in turn regulates a 3.3V output for powering my IR emitter.