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Weird problem with Nest & Mitsubishi heat pump

Hello everyone,
I use a Nest thermostat which is connected to Mitsubishi heat pump (PEAD-A42AA5) through Mitsubishi through Mitsubishi thermostat interface (PAC-US444CN-1). Cooling/fan starts, continues for 10-15 minutes and then suddenly I get an error on Nest saying that there is a problem with a specific wire. Each time it's a different wire. Cooling/fan stops for a few minutes. Then, I get another notification saying that equipment is detected and cooling/fan starts again. What might be the problem? I checked the wiring several times.
Thanks in advance,


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    The Nest

    There was an error rendering this rich post.

  • Ironman
    Ironman Member Posts: 7,376
    Ditch the Nest; it should never be used with modulating equipment.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • SuperTech
    SuperTech Member Posts: 2,166
    Just because you can connect a Nest thermostat to the system doesn't mean that you should.  Use the thermostat that was designed for the equipment.