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cruisair evaporation unit EHMB4C does not heat, releases breaker

Discussion in 'HVAC' started by markus, Apr 12, 2017.

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  1. markus

    markus New Member

    Joined:
    Apr 18, 2016
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    Location:
    germany
    Hi all
    I have a cruisair SMX II system with 3 evaporators (one in each cabin), each controlled using SMXir keypad.
    All units have electrical heating built in.
    One of them does not heat and throw the rccb breaker (is it the correct English word ??) after 1-2 minutes of operation, which lets me think of a short circuit of the heater to ground, at least with some resistance which over the time releases the rccb.
    The question is, can the electric heating unit be repaired or changed inside the EHMB4C?

    thanks a lot for help!
  2. Capt J

    Capt J Senior Member

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    Most cruiseair marine a/cs heat by using a reversing valve to reverse the direction of the freon. Lots of times these reversing valves go bad from lack of use. Does the unit run without tripping the breaker on air conditioning? Sounds to me like your compressor is going bad or another issue if it's tripping the breaker after 1-2 minutes. Usually if the reversing valve is bad it will just blow air conditioning when it's set on heat.
  3. markus

    markus New Member

    Joined:
    Apr 18, 2016
    Messages:
    2
    Location:
    germany
    This type of evaporator does not use reverse cycle heating, but it heats with compressor shut off and using a built in electrical heating unit.
    That unit has a short circuit to ground from either phase or neutral wires, and question was if just the heater can be changed, or if I need to replace complete evaporator unit, which would mean filling the system with new freon.
    See picture, heating element is behind the silver plate.

    Attached Files:

    Last edited: Apr 16, 2017
  4. Capt J

    Capt J Senior Member

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    You should be able to replace the heating element.
  5. Capt Ralph

    Capt Ralph Senior Member

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    Chillers and single state (cool only) compressors can use electric heater elements in the fan or before the fan.
    Pending physical room to reach and work on it, it could be serviceable in place and not have the open the coolant or Freon lines.
  6. Capt J

    Capt J Senior Member

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    Yeah, I assumed since he only has 3 evaporator units that it was not a chiller system. Generally the older split units just used reverse cycle only and the new ones in the last few years do have an add on heating element, but figured it wouldn't be an issue this early in the game.