I have an old in wall AC/heater (brand McQuay, Now known as AMANA) in my rented Apt, which cannot be time-programmed. Also it is not possible use an outlet timer because the AC must be turned on and off via the controller as you can see in the pic.
The controller can be unplugged and taken out which made me think I could possibly change the controller with something newer that have that ability. Is this possible? Otherwise, any ideas on how to time-program it would be much appreciated. enter image description here

  • Dos it have a remote control? – virtualxtc May 2 '18 at 20:47
  • No It does not not but I wonder if it supports one – awm May 3 '18 at 0:47
  • I would seriously doubt if there is anything actually made to do what you are asking. It is however really just a thermostat and fan control so it could be rewired but would probably require a transformer and relays to make it work with an ordinary thermostat. I am assuming that you loose your settings when you unplug it? Otherwise a plug in timer would work. – user76730 May 4 '18 at 0:37

How I hacked my window unit for IOT control:

This (admittedly slightly janky) setup allows me to easily undo the modification in case I need warranty service or I'm going to resell it. I didn't have to use a soldering iron or spend all weekend trying to hack into the control board; I just hijacked the code the AC already runs by lying to the program's inputs.

My window AC had a thick solid copper "wire" centrally behind the intake filter that connected to the thermostat. It's usually placed there so as to sense the temp of the incoming room air more than the outgoing cold air. If that sensor gets hot enough, the AC turns on. This is typical and common. You might have to remove the plastic face of the unit to get to the probe, but you don't have to deeply disassemble the whole thing.

I first cranked the AC thermostat up to 85F, making so that it almost never comes on, unless it gets really hot in the room.

I then taped a small heater to the AC's exposed copper temp probe. you can use a strip from electric socks, a USB drink warmer, or if handy with electronics, use a simple ~150 ohm resistor to short a 5v power supply. You don't need/want more than 1/4 watt of heat.

Wrap the heater and probe tightly with gorilla tape. You should be able to smush it all in-place and keep the cover as expected. The thermostat is almost useless at this point, so it doesn't even need to stay in the air flow, you can tuck it all to the side if needed for the fit.

You might tell where this is going.

To turn on the AC, my smart home system applies 5v to the heater from an arduino-like box. This raises the temp on the sensor above 85 and turns on the compressor.

My smart home uses an external temp sensor to monitor the temp and tell probe heater when to turn on and off. The AC on/off state will be the opposite of the small heater on/off state.

This mod isn't for everyone, but it's probably more approachable for many than splicing into the AC's wiring or trying to clone an IR remote control.

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