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TM 5-4120-270-15
Probable cause
Possible remedy
.improperly adjusted
Adjust louvers and
dampers
(closed) evaporator re-
correctly (table 2-1).
turn and discharge air
grilles or fresh air and
CBR air intakes
Dirty or clogged condenser
Clean condenser coil (para
coil
3-11).
Improperly set thermostat -
Set thermostat to desired
(too high)
ambient temperature.
Damaged or loose evaporator - Check evaporator fans
for
fans damage or looseness.
Replace if defective.
(para 3-28).
Defective fan motor
Replace evaporator fan
motor (para 346).
3-16.
No Heat in "Heat" Position
Probable cause
Possible remedy
Power line failure
Restore power.
Loose connections or de-
Tighten loose connections.
fective wiring in
Repair damaged wiring.
heater or fan circuits
Inoperative evaporator
Replace evaporator fan
fan motor
motor (para 3-36).
3-17.
Reduced Heating Capacity
Probable cause
Possible remedy
Improperly adjusted
Adjust
louvers
and
dampers
(closed) evaporator re-
correctly (table 21).
turn and discharge air
grilles or fresh air and
CBR air intakes
Dirty or clogged air filters
Clean or replace air filters
(para 3-9).
Loose connections or de-
Tighten loose connection
fective leads in the heater -
Repair leads necessary.
circuit
3-18.
Inoperative Compressor Crankcase Heater
Probable cause
Possible- remedy
Air conditioning discon-
Stop unit by turning selec-
nected from power line
tor switch to "OFF",
leave connected to power
line.
Section VI. RADIO INTERFERENCE SUPPRESSION
3-19.
Definitions
a.
Interference. The term interference as used
herein applies to electrical disturbances in the
radio frequency range which are generated by
the air conditioner and which may interfere with
the proper operation of radio receivers or other
electronic equipment, or enable the enemy to
locate the equipment.
b.
Interference
suppression.
The
term
"interference
suppression"
as
used
herein
applies to the methods used to eliminate or
effectively reduce radio interference generated
by the air container.
3-20.
General Methods Used to Attain Proper
Suppression
a.
Essentially, suppression is attained by providing
a low resistance path to ground for stray
currents. Methods used include shielding the
ignition and high frequency wires, grounding the
frame with bonding straps, and using capacitors
and resistors.
b.
In the air conditioner, filters are used to ground
RFI-producing stray currents in the electrical
system. All magnetic contractors and switches
are effectively shielded in metal boxes which are
bonded to each other and to the frame with
grounding straps. The air conditioner frame
is grounded through the junction box to the power line
ground wire.
3-21.
Interference Suppression Components
a.
Primary Suppression Components. The primary
suppression
components
are
those
whose
primary function is to suppress radio frequency
interference. These components are described
and located in figure 3-6.
b.
Secondary Suppression Components. These
components have radio frequency interference
suppression functions which are incidental and/
or secondary to their primary function and am
located in figure 3-6.
3-22.
Replacement of Suppression Components
Refer to figure 3-7 and replace radio frequency
interference suppression components.
3-23.
Testing of Radio Interference Suppression
Components
Test the filters using a continuity tester; replace defective
filters. If the test equipment is not available and
interference is indicated, isolate cause by the trial-and-
error method of replacing each filter in turn until the
cause of interference is located and eliminated.
3-7
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