TM 9-4120-404-14
Section IV. OPERATION UNDER UNUSUAL CONDITIONS
2-15. GENERAL. The air conditioner is designed to operate normally within a wide range of climatic conditions.
However, some extreme conditions require special operating and servicing procedures to prevent undue loading and
excessive wear on the equipment. These unusual conditions and the special steps to be performed are listed in the
following paragraphs.
2-16. OPERATION in EXTREME HEAT. When operating the air conditioner in temperatures of 120F (49C) or higher,
extra care should be taken to minimize the cooling load. Some of the precautions that may be taken are:
a. Check all openings in the shelter or enclosure, especially doors and windows, to be sure they are tightly closed.
Limit in and out traffic, if possible.
b. When possible, use shades or awning to shut out direct rays of the sun.
c. Limit the use of electric lights and other heat producing equipment.
NOTE
Weather stripping, the installation of storm doors and windows (if appropriate),
and insulation of surfaces exposed to the outside is recommended when operation
in extremely high temperatures for extended periods is anticipated.
d. Limit the amount of hot, outside air introduced through the fresh air damper to that needed for ventilation.
e. If the shelter has been closed for an extended period in 90F (84C) or higher temperatures and/or when direct
sun has been hitting the shelter and the air conditioner has been off, these additional steps may be taken:
(1) Open the shelter's door and leave it open if the outside environmental conditions do not adversely affect the
equipment in the shelter, or the mission requirement.
(2) Operate the air conditioner in the vent mode for approximately 5 minutes to remove high temperature air
from the shelter. Then switch the air conditioner to the cool mode. Close the shelter door, if it was left open
during the vent mode.
2-17. OPERATION in EXTREME COLD. When operating the air conditioner in temperatures down to -50 F (-45C),
extra care should be taken to minimize the heating load. Some of the steps that may be taken are:
CAUTION
Do not disturb electrical wiring that has been exposed to extremely low
temperatures. When exposed to cold, both the wire and insulation become brittle
and can easily be broken.
NOTE
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.
a. Check all openings in the enclosure, especially doors and windows, to be sure they are tightly closed. Limit in
and out traffic, if possible.
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