TM 9-4120-360-14
SUCTION
DISCHARGE
10. Check for excessive expansion valve
LOW
superheat.
(continued)
11. Check for plugged for kinked distributor
tube.
12. Check for suction line or evaporator coil
tubing restriction.
13. Ensure dehydrator (falter-drier) is not
clogged.
14. Ensure there is no moisture in refrigerant
system.
Table 4-2. Troubleshooting-(Cont.)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
11. UNIT FAILS TO HEAT
Check mode selector switch for incorrect setting.
Step 1.
Set selector switch to LO HEAT and HI HEAT.
Make sure that temperature control thermostat is set properly.
Step 2.
Set switch at INCREASE.
Inspect for dirty or obstructed air filter.
Step 3.
Clean filter.
Remove top, and check for dirty or obstructed mist eliminator,
Step 4.
Clean or replace mist eliminator.
Disconnect power from the air conditioner before doing maintenance on the electrical system. The
voltage used can be lethal.
With top cover removed, check electrical connections to heating element and thermostat, and visually check
Step 5.
elements for damage.
Tighten loose connections. Replace damaged elements.
Disconnect each element in turn, and check continuity. Also check continuity of thermostat point to point.
Step 6.
Continuity should exist when temperature is below 142F (61C).
Replace faulty heating element or thermostat.
Remove front panel and junction box cover. Tag wires to relay K2 for identification, and disconnect. Apply 28
Step 7.
volts dc to terminals X1 and X2 on relay K2, and check continuity of pairs A1-A2, B1-B2 and C1-C2. Continuity
should exist in each pair. Check continuity of each terminal to ground. Continuity should not exist.
Replace bad relay.
Section V. MAINTENANCE PROCEDURES
4.7.
Fabric Cover (See figure 4-4).
a. Description. The fabric cover is made of vinyl impregnated nylon and is supported on a framework of
aluminum rod around all four sides. The cover assembly is mounted on the air conditioner casing by 18 screws and
washers through eyelets in the fabric. Two tapes are incorporated in the top edge of the cover, and are equipped with
eyelets for holding the rolled-up cover by means of turnbutton fasteners. The cover is fastened in the closed position by
means of a heavy-duty slide fastener.
b. Removal. Remove the fabric cover as follows:
(1) Roll the cover down, and fasten all around with the slide fastener.
4-14
