TM 9-4120-399-14
explanations should be used and understood to be sure that the air conditioner unit will operate
in the best possible manner. Refer to Figure 2-1. for location of operator's controls and
indicators.
a. Before operation.
(1) Thermal Protection for Compresor. Check to see that power cable has been
connected to a source of 208 volt, 3 phase, 4 wire, 400 hertz power, and to the input power
connector on the unit. When possible, power- should be connected to the unit at least 30 minutes
prior to operating in the COOL mode. This is critical when outside temperature is cold and
unit is to be operated in the COOL mode. The compressor is equipped with a warm up heater
and thermostat that will not allow the compressor to operate until the compressor has completely
warmed up. This same heater and thermostat will continue to keep the compressor warm as
long as power remains connected to the air conditioner. The unit will operate immediately (fans
only) in the COOL mode before the compressor has warmed up. However, the refrigeration
systems controlled by the compressor will operate only when warm up is complete (less than 30
minutes). If additional cooling is required before the. compressor has warmed up enough to start,
the fresh air damper can be opened. When compressor reaches safe operating temperature it will
start automatically. Fresh air damper and temperature control thermostat can then be adjusted
to suit.
CAUTION
Under normal operating conditions, if the condenser cover or any other
screen or guard is closed or out of place, damage to the unit may occur.
Do not operate in the COOL mode with the fabric cover pulled down.
Make sure that the fabric condenser cover on the back of the condenser
section is rolled up and secured and that all screens and guards are in
place and unobstructed before operating unit.
(2) Fabric Cover. Check that fabric cover has been unsnapped, rolled up, and secured
with both straps to the two turn button fasteners.
NOTE
Under extreme cold climatic conditions, when blowing snow or
freezing rain might enter and damage condenser section, the unit may
be operated in the VENTILATE, LO HEAT, or HI HEAT modes with
the fabric cover rolled down and snapped in place.
(3) Damper Control. It is normally better to keep the fresh air damper slightly open
and the fabric cover rolled up. This will create a slight overpressure which will provide
replacement oxygen and help reduce room odors.
NOTE
Damper should be closed during extreme weather conditions and
during periods when fast warm up or cooling is necessary.
