Piper SEMINOLE PA-44-180, Maintenance Manual

Page: 175 / 881

5. Start the vacuum pump and open the low side manifold hand valve. Observe the compound, low pressure
gauge needle, it should show a slight vacuum.
6. Continue to operate the vacuum pump until 26 to 28 inches of vacuum is attained on the low pressure
gauge, then extend the operation for another 25 minutes.
7. If the system cannot maintain 26 to 28 inches of vacuum, close both manifold hand valves and observe
the compound gauge.
8. Should the compound gauge show a loss of vacuum, there is a leak in the system which must be repaired
before continuing with evacuation.
9. If no leaks are evident, reopen both manifold hand valves and continue the evacuation for another 30
minutes.
10. Close both manifold hand valves, stop vacuum pump and disconnect center manifold hose from the
vacuum pump.
11. Proceed to charge the system.
— Note —
The system should be charged as soon as it has been evacuated.
CHARGING THE SYSTEM.
Once the system has been completely evacuated, it must be charged utilizing a charging stand (preferred
method) or utilizing the airplane's compressor.
CHARGING STAND METHOD.
— Note —
The following instructions apply to Kent Moore, J23500 charging stand Refer to
Figure 21-29.
1. With the system discharged and evacuated, proceed to hook-up the charging stand.
( Refer to Figure 21-30 )
2. Fill the charging cylinder by operating the valve at the base of the charging cylinder and filling the sight
glass with two pounds of liquid refrigerant.
3. As refrigerant stops filling the sight glass, open the valve at the top of the gauge neck assembly
intermittently to relieve head pressure and allow refrigerant to continue filling the sight glass to the
required amount.
4. When refrigerant reaches the required level in the sight glass, close the valve at the base of the cylinder
and the valve at the bottom of the refrigerant tank. Be sure the top valve is fully closed.
— Note —
If bubbling occurs in sight glass, reopen the cylinder base valve momentarily to
equalize drum and cylinder pressure.
5. Connect the heating element plug to a 110 volt outlet.
6. Turn cylinder sight glass to match pressure reading on cylinder pressure gauge. This scale should be
used during entire charging operation.
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
2 1 - 5 2 - 0 8
Page 21-64
Revised: May 15, 1989
1H7
PIPER AIRCRAFT