Weather stripping, the installation of storm doors and windows, if appropriate, and insulation of
surfaces exposed to the outside is recommended when operation at extremely low temperatures for
extended periods is anticipated.
d. Before attempting to start the unit in the COOL mode or when fresh air is being used during the HEAT,
mode, be sure that cover is rolled up and all exposed air openings are clear of ice and snow.
e. When the unit is to be used at low temperatures in the COOL mode, the low refrigerant pressure cutout
switch must be jumpered. Contact organizational maintenance.
f. Be sure that all dampers are operating freely,
g. If unit is not being used or is being used in the HEAT mode without fresh air, close (roll down) and secure
the fabric cover.
2-13. OPERATION IN DUSTY OR SANDY CONDITIONS
Dusty and sandy conditions can seriously reduce the efficiency of the air conditioner by clogging the air
filter, mist eliminator and coils thereby causing a restriction on the volume of airflow. Accumulation of dust or
sand in the condenser coil and/or in the compressor compartment may cause overheating of the refrigeration
system. Dust or sand may also clog the condensate trap, and water drain lines. Some of the steps that may be
a. Frequent cleaning of filters, mist eliminator, coils and all other areas of dust and sand accumulation. In
extreme conditions, daiIy cleaning of filters may be necessary.
b. Limit the amount of dusty or sandy outside air introduced through the fresh air damper to that essential
c. Roll down and secure the fabric cover on the back of the cabinet during periods of shutdown.
2-14. OPERATION IN UNUSUALLY WET CONDITIONS
The air conditioner is designed for normal exposure to the elements, so it is reasonably waterproof. Some of
the steps that should be taken in an extremely wet climate are:
a. More frequent inspection and cleaning of the mist eliminator, condensate trap, and drain lines to insure
proper drainage and prevent accumulation of water inside the cabinet.
b. Roll down and secure the fabric cover on the back of the cabinet during periods of wet, windy weather
when the air conditioner is not in operation.
c. Roll up and secure the fabric cover during dry spells when the air conditioner is not in operation so that
the interior can dry out and condensation will not accumulate.
2-15. OPERATION IN SALT AIR OR SEA SPRAY
Salt air or sea spray may cause many of the same clogging problems as encountered when operating in a
dusty or sandy environment. In addition, the nature of salt presents serious corrosion problems. Frequent
cleaning is necessary during which all exposed surfaces should be thoroughly spray rinsed or sponged with
fresh water to remove salt encrustations. The fabric cover on the back of the cabinet should be rolled down and
secured during all periods when the air conditioner is not in operation.
2-16. OPERATION UNDER EMERGENCY CONDITIONS
a. CBR Hazard. When operation is anticipated under potential chemical-biological-radiological (CBR)
conditions, a CBR filtering unit should be connected to the fresh air intake. It maybe necessary to remove the