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 TM 55-1905-220-14-8
4-29. 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.
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 9. 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 4-299(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 (105 (40.6 ) or above). Maximum permissible crankcase temperature,
F
C
measured at seal housing, is 212 (100 ). A crankcase warmer than normal (above 180
F
C
F
(82.2 )) may indicate a clogged liquid line strainer or other trouble. Refer to Volume 3. A
C
crankcase cooler than normal (well below 105 (40.6 )) may indicate liquid refrigerant
F
C
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