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Split System Noise - Mitsubishi Three Head

I have a fairly new Mitsubishi split system with three interior heads, installed by a Diamond dealer with a good local reputation. We had some issues with the initial installation not heating very well and then having cooling issues in the summer which was finally tracked to a leak in the outside unit. They replaced it and the air conditioning worked fine. In cold weather now they can produce 100+ degree output.

This winter I have noticed more noise coming from the inside units. Essentially it only happens when it gets below freezing, happens more frequently when it gets colder and I believe it's also noisier. There is a loud whistle, like high pressure liquid moving through a pipe, which goes on for 10-20 seconds, followed by lower gurgling sounds. It can wake me up at night, and conversation has to stop.

We don't have too many cold days here, and I wanted the tech to hear it so between the weather and schedule, I finally got their senior tech out yesterday. Of course it was warmer, just about freezing, but before he left it did make some noise.

He says that the issue is the defrost cycle. It gets noisy as the system reverses flow to heat up the coil outside, which makes sense. Normal noises are understandable from machinery, but it seems to me that, especially when it's colder, it's unacceptably noisy.

Tough question, because my too noisy might be someone else's minor issue.

He's going to look into possible ways to quiet it down, but doesn't hold out much hope. Any suggestions?

Comments

  • GWGW Member Posts: 3,727
    Terry, with the grand assumption the stuff is installed professionally:

    that is all described in the user guide. Basic and simple velocity noises, the outdoor unit is “bleeding” pressure to “off” heads. When I sell ductless I explain the mechanic differences between single and multi. If you want “less noise” DO NOT but a multi zone. Doesn’t matter who the manufacturer is.
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    www.wilsonph.com
    [email protected]
    HVACNUTIronmanSuperTech
  • pecmsgpecmsg Member Posts: 1,387

    GW is just trolling me since he didn't know what to do either.

    I replaced my evaporator Saturday and all the noises went away. Facts trump fiction. There is not anyone here who has an idea what you are hearing. Most of them profit off the defective equipment Mitsubishi sells. I am not tied to a brand, and will give you an honest answer.

    Your happy Fine

    Give it a rest
    IronmanGW
  • SuperTechSuperTech Member Posts: 1,303
    > @Terrywshum said:
    > I replaced my evaporator Saturday and all the noises went away. Facts trump fiction. There is not anyone here who has an idea what you are hearing. Most of them profit off the defective equipment Mitsubishi sells. I am not tied to a brand, and will give you an honest answer.

    I don't think replacing an evaporator for a couple hundred bucks on a brand new system counts as making a profit. If anything it's very bad for business. We prefer not having work of that nature.
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