How to repair my Marine air conditioning

Discussion in 'Services & Employment' started by Mabruteam, Feb 4, 2011.

  1. sdowney717
    Joined: Nov 2010
    Posts: 955
    Likes: 54, Points: 28, Legacy Rep: 274
    Location: Newport News VA

    sdowney717 Senior Member

    I have a 37 foot sedan cruiser with lots of glass so the sun heats up the cabin.

    I have a cruisair 16K BTU split system.
    This uses the older style 3 rotary knobs.
    The suction line broke at compressor connection.
    The line was 3/8 too small from the original install.
    I upped to the 1/2 inch copper line and insulated the line.

    I took the compressor home and cleaned and painted and installed an APR5 supco potential relay, old relay did not click off the start capacitor.

    I installed a Sporlan catch all C083 filter drier in the compressor suction line after the heat pump valve, removing the cigar filter drier.
    I installed a glass port to see bubbles in the high pressure line at the compressor end to view the stream.

    I checked the compressor suck down vacuum pulls 27.5 inches.
    I checked the internal compressor valves, they hold perfectly.
    I drew a vacuum and it held perfect for 3 days.
    I recharged with hydrocarbon blend r502a.

    some running data
    amp draw of total ac system about 14 amps
    volt drop to 101 vac when it runs off shore power

    water inlet temp 83
    water discharge temp 89

    When fully charged so that there are no bubbles,
    ambient air = 88
    suction low pressure = 84
    discharge high pressure = 235

    lower cabin evaporator using k type probe
    51 coil metal temp
    56 air temp in front of air stream coming out
    84 air temp going into evaporator

    upper cabin where it gets more heat from sun
    68 air temp in air stream coming out
    88 air temp going in

    63 temp on copper condense pipe at compressor
    84 PSI = 56 temp chart
    63-56 = 7 degree superheat.

    94 condensor temp
    235 psi = 122 temp chart
    94 - 122 = -28 degree subcooling ???????
    Or I have it backwards
    122-94 = 28 subcooling

    Now before the copper tube broke years ago, and charged with r22, the boat also can only cool well if sun is not beating down on it.

    So with new hydrocarbon blend, not a lot seem to have changed. It just stays hot feeling with the sun on the boat.

    Is the system working like it should or like it can?
    Or is it not cooling like it should?
    I was told the hydrocarbon refrigerant ought to be just a s good as r22
    Takes maybe slightly more than 1/2 lb to charge.
    Should the bubble charge method be ignored?

    Is it overcharged?
    Give me your feelings what ever they are?
  2. sdowney717
    Joined: Nov 2010
    Posts: 955
    Likes: 54, Points: 28, Legacy Rep: 274
    Location: Newport News VA

    sdowney717 Senior Member

    well zero response to the slight overcharge issue, as I figured!

    MAYBE leans toward ever so slight overcharged. This unit has a receiver right after the suction port which will help prevent slugging.

    Anyway so far I am happy enough about it working. The sunlight creates a green house effect in the main cabin. I have some canvas covers for the front windows I need to put up to aid against sun caused heating.

    I charged to the max cool I can read on the evaporator and the sight glass is full.
    The internet is a great resource.
  3. jonr
    Joined: Sep 2008
    Posts: 721
    Likes: 11, Points: 0, Legacy Rep: 57
    Location: Great Lakes

    jonr Senior Member

    I'v been told that adding a TXV to systems that don't have one helps.
  4. sdowney717
    Joined: Nov 2010
    Posts: 955
    Likes: 54, Points: 28, Legacy Rep: 274
    Location: Newport News VA

    sdowney717 Senior Member

    A TXV definitely is a big improvement with proper metering of refrigerant into the evaporator. How one could be added to a cruisair evaporator, I am not sure.
    It must involve some silver brazing and cutting tubing to remove the orfice and a little redesign.
    You could likely take it to someone and have that done.

  5. ericoh88
    Joined: Jan 2014
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Singapore

    ericoh88 New Member

    Relay for Marine Air System - Passport II


    Recently the Marine Air System stop giving out cool air. A quick check showed the water pump is not working.

    I remove the 110v supply wire from the controller board Passport II to test if the pump is working. The water pump is working. A further trace showed the compressor is not running. A quick knock on the relay NT90RHAS5CB and the compressor started and the water pump started. For now it seems a faulty relay to be the cause. The air cond was installed in 2003 in Fort Lauderdale.

    So I need some help in sourcing this elusive relay.

    NT90RHAS5CB 30A/240VAC/2HP 30A/14VDC DC 5V

    Appreciate your thoughts on this matter.

    Thank you.
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