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Busy signal

I have a Mitsubishi hyper mini split.
When the unit is in heat mode the wall unit i
s making a busy signal sound. This noise goes
away in cool mode. The sound is loud enough
to keep you awake at night, I have turned up
the air cleaner to drown out the noise.
Anyone ever run into this.


  • motoguy128
    motoguy128 Member Posts: 394
    Some have a minimum lineset length and can make noise if it’s too short. I think liquid velocity becomes too high.