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LOW SUCTION AND DISCHARGE PRESSURE - TM-5-4120-361-14_85
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TM-5-4120-361-14 Air Conditioner Vertical Compact 18 000 BTU/HR 208 Volts 3 Phase 50/60 Hz (Model 18K 208 3 60) Manual
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Brazing - TM-5-4120-361-14_87
TM 5-4120-361-14 Section  III. GENERAL MAINTENANCE 5-5. General. This section contains general servic- ing instructions that otherwise would have to be repeated several times in this  manual. 5-6. Testing for Leaks. The air conditioner can be tested for refrigerant leaks by the use of an elec- tronic leak detector, by the halide test or by the soap bubble method. The  pre- ferred method is use of the electronic leak  detector. If sufficient pressure is not present in the system to accom- plish an adequate leak test, add dry nitrogen at the receiver charging valve to increase the system pressure to 300 psig, then conduct the leak test. If the system is totally discharged, to conserve leak test refrigerant, pres- surize the system with R-12 to 72 psig, isolate the compressor by front-seating the service valves (1 and 2, figure 3-2). At the receiver charging valve pressurize the system with dry nitrogen to 300 psig, then conduct the leak test. (1) By Electronic Leak Detector. Using a G.E. Type H-2 Leak Detector, or equivalent, proceed as follows: (a) Turn on and calibrate the leak detector as described in the in- structions supplied with the instru- ment. (b) Slowly pass the detector probe tip over the sweat fittings, mech- anical couplings and valves in the re- frigerant circuit. If refrigerant is leaking, detector will provide a visible or audible signal. (c) Use the soap-bubble method to localize the leak to a defective com- ponent or connection. (2) By Halide Leak Test. Using a propane flame halide leak detector, pro- ceed  as  follows. (a) Slowly pass the exploring tube on the torch over the sweat fit- tings, mechanical couplings and valves. If refrigerant is leaking, the flame will be affected as follows: INSTRUCTIONS Small leak --   flame changes from blue to green Large leak --   flame changes from blue to dense blue with reddish tip Massive leak- may extinguish flame (b) Use the soap-bubble method to localize the leak to a defective com- ponent or connection. (3) By Soap  Solution  Method. Using either a prepared bubble-type leak de- tector compound or a solution of hand soap in water, proceed as follows. (a) Apply the solution to all points of possible leakage, and watch for bubble formation indicating a re- frigerant  leak. NOTE Allow  solution  to  remai joints long enough for leaks to form noticeab bles. n on small e bub- (b) Wipe solution from joints and mark spots where leakage is observed. 5-7. Refrigeration System. a. Opening System. When the refrig- eration system must undergo maintenance that requires the system to be opened for removal of parts, the system must first be discharged (para 6-3). After the repair has been made and all solder- ing completed, the system must be tested for leaks and charged (para 6-3). b. Removal of Parts. When the re- frigeration system must undergo main- tenance that requires the refrigerant system to be opened for removal of parts, the system must first be dis- charged and purged (figure 6-1). After the repair has been made and all solder- ing completed, the system must be tested for leaks and charged (para 6-3). Ex- cept for flare nut connection, all the tubing attachments in the refrigeration system  are   “sweat-joints” which are opened by heating with a brazing torch. During  unseating,  shield  the  wiring, insulation, painted metal, and valves from the heat of the torch. Use wet 5-6

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