ARMY TM 9-4120-380-14
AIR FORCE TO 35E9-136-21
5.19. PUMP DOWN This task covers service
Tool kit, service, refrigeration unit (Item 1, Appendix B
a. Turn MODE SELECT switch to OFF
b. Remove suction, discharge, receiver, and hot gas bypass protective caps.
c. Backseat (counterclockwise) suction and discharge valves
Death or serious injury may result if personnel fall to observe safety precautions. Use
great care to avoid contact with liquid refrigerant or refrigerant gas being discharged
under pressure. Sudden and Reversible tissue damage can result from freezing Wear
thermal protective gloves and a face protector or goggles in any situation where skin-
eye-contact is possible.
d. Connect service manifold to compressor suction and discharge valve (paragraph NO TAG, Steps c and d).
e. Crack suction valve so gauge will function.
Never pump the system down below 1 to 2 lbs. gauge pressure A slight positive
pressure should always be left in the system. This prevents air and system damaging
moisture from being drawn in through very small leaks.
Never pump the system down to a vacuum and then open to atmosphere. A vacuum m
the lines, when opened, would fill the system with air carrying undesirable amounts of
moisture into the system.