SMB Air Conditioner
12 VDC Owner’s Manual 9/09
Page 3 of 13
Chapter 2 - Routine Maintenance
Air Flow
Proper air flow is critical to the operation of the air conditioner. All grilles, both supply and return, must
never be blocked by objects such as bed linens, duffel bags, tackle boxes, etc.
Return Air Grille(s) and Filter(s)
Return air grilles are available in both aluminum and wood in standard configurations. They do not have
adjustable louvers and are available with and without filters. Return air filters should be cleaned
regularly. The filter shipped with your unit is located in front of the air coil can be cleaned with a
vacuum cleaner or rinsed with fresh water.
If your unit’s return air grille has a filter, be sure that your boat builder or installation technician has
removed the standard filter that comes with every unit in front of the evaporator (air) coil. Two filters
can unduly restrict air flow and in some cases, cause problems with performance. Use EITHER a return
air filter grille or the supplied filter, never both.
Depending upon the floor plan, your boat’s space constraints may dictate that a unit be installed in an
area that makes it difficult to access and clean the filter. If this is the case, and you do not have a return
air filter grille, you should consider removing the disposable unit filter and upgrading to a return air
filter grille.
NOTE: Blocking the return air grille of neglecting filter cleaning will result in a restriction of air flow.
After a period of time, ice will form on the evaporator coil and a resultant LOW PRESSURE FAULT
shutdown.
Supply Air Grille(s)
Some installations will have more than one supply air grille. Standard main supply air grilles are
generally made of aluminum or wood frames with two or four-way adjustable louvers. These may be
adjusted to direct air flow from the grille to ensure a uniform cabin temperature. Main supply air grilles
should never be closed at any time while the unit is running. The secondary supply air grille more
frequently will be a 4” (102mm) round plastic design, but they can also be of the aluminum or wood
frame standard configuration and are usually located out of the main salon, galley, dinette area. These
may, depending upon the style you or your boat manufacturer has chosen, be closable. During the day, it
may be closed should you like more air directed to the main living area. Consult with your local Marvair
Marine service representative if you are unsure which is the main supply grille on your boat. Closing off
the main supply air grille or secondary air grille, in some applications, may restrict air flow and cause
ice up of the evaporator in the cooling mode.
Condensate Pan and Lines
The condensate and lines can develop an algae type growth. Periodic inspection and treatment with a
mild solution of bleach and water poured into the condensate pan will keep the condensate pan and lines
clear.
Sea Water Strainer
The seawater strainer is available in several configurations – bronze or plastic. Yours has been sized in
accordance to system specifications for volume of water required. It is used to prevent debris such as
eelgrass, sea weed, leaves, etc., from passing through the system water lines and condensing coil. These
items could lodge themselves in the water supply causing several possible shutdown faults, and left
