This seems to fit this thread got a email from Marinaire today guess some may not know this but I will pass it on this goes for all units!
Never got one from Cruise air
IMPORTANT Reminder to all Customers
Reverse cycle heat pump marine air conditioners will not work once the water temperature is too cold.
Therefore, DO NOT operate the units at heating, cooling, auto or dehumidification modes once the water temperature is below 40 degree Fahrenheit (or 5 degree Celsius)
Operating the units at heating mode once the water temperature is below 40 F will cause irreparable damages. The water will freeze inside the tube, expand and crack the coil.
Additionally, once the ambient temperature ( air temperature) gets below 35 , The unit should not be operated at any mode (Cooling, heating, dehumidification or auto mode) . The air conditioning unit should be winterized immediately
WINTERIZING THE AIR MARINE AIR CONDITIONER
To avoid any freezing during winter, winterization is necessary. Do not leave sea water, fresh water or
air in the system . Fill antifreeze solution though the intake, strainer, pump and coil and water outlet
(entire system)
! Warning: Collect all discharged liquids and recycle or dispose of in a proper manner.
Please feel free to contact us for any question.
Best regards,
Sam Zengin