Quick update on the project...
Aircons are HVAC systems and receive the full state in every message - i.e. if you press temp down 1 degree, the remote actual sends the temp setting, the fan setting, the swing setting etc every time. Previously I had to use a work around because the free android MQTT clients I found, could not send settings from multiple controls in a single message. I've written my own now, am iterating to remove the unneeded complexity.
I've developed a basic MQTT android app that can send the full state. I've started using JSON payloads in the MQTT messages, and I'm rewriting the firmware on the ESP-01 as well.
I'll write this up more completely another time and upload the code to GitHub, but for now here is a couple of screenshots,
And the latest iteration of the device... I've changed the power source to a 18650 instead of 2 AA... after losing 3 hours on a bug that was actually a power issue... I've also broken out the reset pin so I can add back the ESP Deep Sleep function to extend battery life.