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I have a Midea duct HVAC that has only the option of wired thermostat remote and it's not smart.

I want to build something smart so I can turn on / off the AC or the heating remotely, but I don't know where to start from and if I can build something or it's something internal that only Midea can do it.

Here is the picture with the wires diagram enter image description here

The remote does not have any infrared. I don't know what is that infrared pipe of wires A and B.

The 5 wires are:

  • A-B = infrared pipe
  • C = +5v
  • D = GND
  • E = RUN

Model of the remote control: kjr-10b/dp(t)-5b

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    Sorry but there's just not enough info in your diagram. These are just assembly instructions, the manual tells nothing about the compatibility with devices which are not shipped with the HVAC. Commented Jul 3, 2019 at 12:02
  • @DmitryGrigoryev I am thinking talking to Midea maybe they can provide some details. What info should I get from them in order to be able to create something custom? Also I have added the remote model to the question if helps. Thanks. Commented Jul 3, 2019 at 13:00
  • Maybe asking them for details will work. My point is, unless you know what you need to do electrically, asking on the RPi site will not bring you much. When you know that you must e.g. toggle RUN between 0 and 12V, you could ask how to do that. Commented Jul 3, 2019 at 13:03

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Welcome. I do not have a clue to what you have but start with a multimeter and place it across the contacts of the thermostat and measure the voltage when it is on and when it is off, this will tell you the control voltage and if it closes to turn it on. If it reads about zero which I expect the contact closes to turn the unit on. This would be the NO contact on the relay. When it is off it will tell you the control voltage, expect about 5V. Then remove the run wire and measure the voltage using ground as reference same for the other measurements, it will probably be about 5V. At this point you should know if it is safe to connect the run to the +5. When doing this it should start. To interface to your Pi you can use a simple relay. The relay contacts replace the thermostat.

If you do not have a multimeter you can get an inexpensive one for less than $10.00 US.

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