Heating the Cabin - Reverse-Cycle AC/Heat

Discussion in 'General Maintenance/Repair Questions' started by Scholarship, Oct 18, 2006.

  1. Scholarship

    Scholarship New Member

    58
    Oct 4, 2006
    Norman, OK
    280 Sundancer
    Twin 4.3L MPI with Alpha Drives
    I have a question about using my reverse-cycle AC/heat to heat the cabin while away. I have a Cruisair SMXir keypad and expected that when I set the temperature to 55 degrees (lowest available temperature setting), set the control to heat, and the fan to auto, that the unit would not come on unless the temperature in the cabin dipped below 55 degrees.

    However, in a test yesterday afternoon, with the cabin temperature at 74 degrees, the unit still operates with what feel like cool air coming out. I ran it for oven an hour and it never stopped running. What am I doing wrong or what's not functioning properly?
     
  2. Dave S

    Dave S Well-Known Member TECHNICAL Contributor

    Oct 3, 2006
    Upstate South Carolina
    Boatless
    Boatless
    The fan on these units never turn off and that could be what you are experiencing. I noticed the same thing on my new 260DA and inquired of our HVAC tech at the Marina why my unit was constantly running. He showed me in his factory shop manual that the way they are designed. Once they are turned on at the thermostat, the fan will run whether the compressor runs or not. Therefore, if you are sure your system's water pump and A/C compressor is not running, then the unit is probably functioning OK. I was also told by the tech that these units are not very efficient once water temperature drops into the forties. He therefore recommended a seperate cabin heater to keep the cabin warm. I bought one of these http://www.westmarine.com/webapp/wc...0/cabin heater/All_2/mode+matchallpartial/0/0
     
  3. Scholarship

    Scholarship New Member

    58
    Oct 4, 2006
    Norman, OK
    280 Sundancer
    Twin 4.3L MPI with Alpha Drives
    DaveS...my water pump and A/C compressor were not running during my heating test so all could be OK. I will re-test once we get some cooler temperatures. However, I could swear that the fan is not always blowing when in cooling mode (which is all I've been using so far). True, I've only owned the boat for a month but I recall the fan shutting down once it reached the desired temperature. I guess I'll have to check that out on my next visit. As for the West Marine unit, will you leave it on and in the antifreeze setting while you're away from the boat, even if you plan on being gone a week or more? Thanks for the help.
     
  4. Dave S

    Dave S Well-Known Member TECHNICAL Contributor

    Oct 3, 2006
    Upstate South Carolina
    Boatless
    Boatless
    My fan runs in heating or cooling mode.

    As far as the cabin heater goes, I plan to let mine run 24/7 to keep the cabin at 60-65 degrees. These are powerfull little units and they should be capable of doing that.
     
  5. skolbe

    skolbe Active Member

    Oct 3, 2006
    St. Louis, MO
    320 Sundancer, Mercury 310 Sport Inflatable Tohatsu 6HP
    350 Mag V-Drive - Kohler 5ecd
    The fans always run on these units.
     
  6. CJ Martin

    CJ Martin Member

    762
    Oct 4, 2006
    Great Mills, MD
    2002 320DA
    350MAG Horizons / V-drives
    I'm not sure we have exactly the same unit, but on mine the fan can be set to run all the time or only when the unit is heating/cooling. On all the time is the default, and you can change this by following the programming options in the manual.

    -CJ
     
  7. Dave S

    Dave S Well-Known Member TECHNICAL Contributor

    Oct 3, 2006
    Upstate South Carolina
    Boatless
    Boatless
    CJ is correct on this one but there is one caveat.

    By way of explanation, I never got my manual for my Cruisair System when my boat was delivered so I was relying strictly on what the Tech told me when I asked him the question on the fan. (The dealer has ordered the manual for me). So after reading CJ's comments, I did some research this morning and saw that the manual is available in pdf format on Cruisair's site so I downloaded it http://www.cruisair.com/sheets/L-2362.pdf and on page 10 they explain how to overide the "fan always on" condition. The "caveat" here is if you intend to have your fan turn off when the compressor does, they recommend relocating the Thermistor from the return air grille to a cabin wall where it can better sense the temperature.
     
  8. jrcinnh

    jrcinnh New Member

    368
    Oct 4, 2006
    Lake Winnipesaukee, NH
    v358
    twin 5.7 vp duoprop
    CJ and DavesS are right, it's easy to change the mode so the fan only comes on when the unit is heating or cooling. But if you do it you will get weird operation due to the sensor location. On my boat the sensor is on the intake of the unit which is under the v-berth.

    If heating, when the fan stops there is no air flow under there and there's a big compressor keeping it warm. It stays warm under there long after the cabin is cold.

    When cooling the lack of airflow causes the cool sensor to get wet with condensed water and mess up the operation again.

    I never thought or read about moving the sensor out into the cabin living space. That sounds like an easy wiring job, I'm going to try it next spring.
     
  9. thunderbird1

    thunderbird1 New Member

    365
    Oct 4, 2006
    Pacific Northwest
    Dave: Thanks for the manual link! I didn't get any documentation with my boat either.
     
  10. Scholarship

    Scholarship New Member

    58
    Oct 4, 2006
    Norman, OK
    280 Sundancer
    Twin 4.3L MPI with Alpha Drives
    Relocating the thermistor was the trick when programming the keypad to have the fan run only when the comnpressor is running. I tried it last night and it worked great. Luckily the thermistor had about 36 inches of spare wire that was neatly wrapped so all I had to do was unwrapp it and snake it up behind the seat cushion in the dinette (my AC/Heat unit is under the port dinette). No rewiring at all. Thanks for all your help.
     
  11. Jerry Minton

    Jerry Minton New Member

    6
    Jan 18, 2009
    Have a 550 Sea Ray. Salon units compressors shut down & error message Low PS comes up. Have reset to factory settings & tried to start up. Goes thru start-up for 4 tries & then message appears. Think I may need freon. 2nd problem is how to access unit to check. How does curved sofa come out? Any ideas would be appreciated. :smt100
     
  12. Jimmy Buoy

    Jimmy Buoy Active Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    I had the same LO...PS message on mine last fall. It had low freon due to a leak in the coil. :grin:
     
  13. mrsrobinson

    mrsrobinson New Member

    Mar 9, 2006
    Richmond, Virginia
    1995 Sea Ray 330DA - Sold
    2001 Regal 3780 - Sold
    Big ones
    If I recall correctly our unit has 3 settings; ac, heat or both. When on both it keeps the cabin at the temp you set using heat or ac.
     
    Last edited: Jan 19, 2009
  14. osd9

    osd9 New Member

    Oct 3, 2006
    MidAtlantic
    2003 410DA
    Caterpillar 3126-TA w/ ZF 80-IV
    Trigger!

    read this...

    http://clubsearay.com/forum/showthread.php?t=3687&highlight=trigger
     
  15. vetteboy

    vetteboy New Member

    112
    Nov 11, 2008
    Florida
    300 Sundancer
    Two
    It would help to know where you are located..Maybe the water is just too cold.
     
  16. Jerry Minton

    Jerry Minton New Member

    6
    Jan 18, 2009
    Located on Tenn. River in Decatur, AL.
     
  17. Jerry Minton

    Jerry Minton New Member

    6
    Jan 18, 2009
    In follow-up, boat is 1995 model. Looks as if I have low freon in both salon units (seems very unusual). Compressors do come on, run for 2 min., shut down 1 min. & water does flow. Looks like I have to access compressors. I am totally baffled as to how to remove L shaped sofa from salon as I have not been able to figure out how it's installed. Has anyone removed sofa?
     
  18. Robski97

    Robski97 Well-Known Member

    Jan 15, 2007
    North Bellmore, NY
    44DA
    Cummins QSC 8.3's
    Jerry. Whats the water temp and the cabin temp ?? LOW PS would not come from a bad trigger or no water flow . Leaks are very rare. 2 units doing same thing have to look at wahts common. So reply with temps and is the filter clean ???

    Rob
     
  19. mrsrobinson

    mrsrobinson New Member

    Mar 9, 2006
    Richmond, Virginia
    1995 Sea Ray 330DA - Sold
    2001 Regal 3780 - Sold
    Big ones
    "Has anyone removed sofa?"

    You might be better served to start a separate, new, discussion on this part of your issue so you get more responses. Buried in here folks will not see this.
     
  20. osd9

    osd9 New Member

    Oct 3, 2006
    MidAtlantic
    2003 410DA
    Caterpillar 3126-TA w/ ZF 80-IV
    Oopss...I stand corrected....I had a HI PS when my trigger went bad.....good catch Rob...:thumbsup:
     

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