14-17. AIR-CONDITIONING SYSTEM SERVICING (R-12) (Cont'd)
b. Manifold Gauge Set Removal
Before attempting to disconnect manifold gauge set hoses, service
valve shafts must be returned to their "back-seated" position.
Failure to do so may result in injury to personnel.
Never operate A/C system with service valves "front-seated"
Turn each service valve shaft (11) counterclockwise to "back-seated" position.
Loosen low pressure gauge valve (1) and high pressure gauge valve (2) slowly, allowing refrigerant
to escape from hoses (4) and (6) through hose (5).
Disconnect low pressure gauge hose (6) and high pressure gauge hose (4) from service valves (7)
Install two capnuts (9) on two service valve ports (10).
Install two dust caps (12) on service valves (7) and (8).
Disconnect battery ground cable (TM 9-2320-280-20).
Install manifold gauge set (refer to task a.).
Insert center hose (5) of manifold gauge set (3) in a catch bottle or can.
Do not allow refrigerant R-12 to escape too quickly. Lubricating oil
When high pressure gauge and low pressure gauge read "zero",
Turn low pressure gauge valve (1) and high pressure gauge valve (2) counterclockwise slightly to
permit refrigerant to slowly escape through center hose (5) until gauges read "zero".
Turn service valve shafts (11) to "back-seated" position to prevent air and moisture from entering
Measure any significant accumulation of oil in discharge bottle and record for oil charging
Disconnect manifold gauge set (refer to task b.).