TM 9-4120-357-14
Table 3-1. Troubleshooting (Cont')
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
CAUTION
Bubbles may appear in the sight-glass when the hot gas by-
pass valve is in operation with normal charge. To verify that
the refrigerant charge is low, operate unit at full load condi-
tion without the pass open. If bubbles appear at full load
condition with bypass closed, addition of refrigerant is re-
quired.
Step 8. Check sight-glass liquid indicator for bubbles or milky appearance of liquid.
If bubbles are observed, report condition to unit maintenance.
Step 1. Check selector switch setting.
Set selector switch to HI HEAT.
Step 2. Check fresh air damper position to be sure that it is not admitting too much cold air.
Close fresh air damper.
Step 3. Check evaporator intake and discharge grilles for proper (open) position.
Open grilles.
Step 4. If thermostat is remotely located, check to be sure that it is not close to light bulbs or
other heat-producing equipment.
Step 5. Check function of the thermostat by turning to higher or lower settings.
Notify your supervisor.
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