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 TM 55-1905-219-14-8
4-28. AIR CONDITIONING SYSTEM - MAINTENANCE INSTRUCTIONS (Continued).
(c) If the condenser cannot stand idle and must be tested immediately, first flush and vent condenser
for at least fifteen minutes to purge any foreign gases. Then, close refrigerant inlet and outlet valves and all
water valves. Drain condenser water side through drain valves or plugs in bottom of water heads. Test for
presence of refrigerant-12 in water heads through drain openings. If this test detects a refrigerant leak, remove
water heads and test individual tubes and tube sheets for leaks.
(4) Leaks to Overboard Discharge.
(a) Where a relief valve connected to an overboard discharge line is provided, refrigerant may be lost
without detection if the relief valve is not seated tightly.
(b) To test for a leaky relief valve, remove a plug from overboard discharge line or disconnect a section
of line downstream of relief valve. Test for leak by applying exploring probe or tube of leak detector to open
connection.
s. General Compressor Maintenance.
(1) Lubrication.
Instructions on the compressor lubrication system, including routine maintenance normally performed
by operating personnel, are given in paragraph g. Refer to these instructions for procedures on adding or
removing oil, data on proper oil level and pressure, and other information on compressor lubrication.
Troubleshooting charts for the lubrication system are given in Volume 3.
NOTE
Check operation of oil pressure safety switch at least monthly. Refer to paragraph 4-28g(8).
(2) Operating Pressures and Temperatures.
When abnormal operating pressures and temperatures are observed, refer to troubleshooting charts
given in Volume 3. Some of the more important temperature and pressure indications related to the
compressor are also discussed below.
(a) Crankcase Temperature.
After the compressor has been started, the crankcase should warm up so that it can be felt by the
hand (105F (40.6 ) or above). Maximum permissible crankcase temperature, measured at seal housing, is
C
212F (100 ). A crankcase warmer than normal (above 180F (82.2 )) may indicate a clogged liquid line
C
C
strainer or other trouble. Refer to Volume 3. A crankcase cooler than normal (well
4-872
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