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 TM 55-1905-219-14-11
5-144. REFRIGERATOR/FREEZER - MAINTENANCE INSTRUCTIONS
(Continued).
LOCATION
ITEM
ACTION
REMARKS
SERVICE (Cont)
temperature. In the case of a refrigerant overcharge, the discharge pressure will return to the normal figure which
corresponds to the pressure, that is normal for the existing room temperature. However, if air is present, it will be seen
that the head pressure does not return to the normal figure when the unit has cooled down to the existing room
temperature.
h.
Purging air.
(1)
An excess of refrigerant or the presence of air in the system will require a purging operation. This
operation is done as follows:
(a) Disconnect the pressure gauge at the discharge service valve and open the discharge valve so
that air is allowed to escape slowly.
(b)
At this point, the service man can purge the required amount.
TEST AND ADJUSTMENTSI
4.
Refrigerator/Freezer.
a.
When the chill box is first installed, place a thermometer inside. Let the chill box run for three hours, Within
one half hour, the temperature should be 45 above zero.
b.
If the proper temperature is not obtained, install a gauge on the low-side of the condensing unit. The back
pressure must show 3 to 6 lb. pressure. The head pressure gauge must show 85 to 90 pound pressure. If the low-side
gauge shows a deep vacuum, then this is evidence of a gas leak and moisture in the system. In this case, the leak must
be located and silver soldered. The proper way to locate a leak is with a Halide torch. When using a torch, use a small
flame and be sure reactor plate is in good condition. After repairing leak, the system must be recharged. In order to
recharge the system, the following must be done:
(1)
Front-seat liquid line service valves.
5-1464
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