Piper SEMINOLE PA-44-180, Maintenance Manual

Page: 177 / 881

Figure 21-30. Charging Hookup
2. Place the refrigerant container on a scale to observe the amount of refrigerant entering the system. Open
the high pressure valve and add as much refrigerant as possible.
3. Close the high pressure valve. start the engine and operate it at 900 to 1000 RPM.
4. Operate the air conditioner and set controls to maximum cooling.
5. Open the low pressure valve and complete charging the system.
6. Close the low pressure valve after two pounds of refrigerant has been added to the system.
7. With the system still operating, observe the sight glass in the top of the receiver-dehydrator by removing
the plastic plug.
8. The sight glass should be clear of any bubbles or foam. If bubbles or foam are seen passing through the
sight glass. it is an indication of a low refrigerant charge in the system and more refrigerant is required.
This check should be made with OAT of 70° F or higher and with the air conditioner opening.
9. If more refrigerant must be added to the system, open the low pressure valve and increase engine speed to
2000 RPM and observe the sight glass. After the sight glass has cleared, close the low pressure valve and
observe the pressure gauges. At 1000 RPM the gauge pressure should be 15 to 20 psi on the low side and
150 to 200 on the high side.
— Note —
Suspect leaks or an inaccurate scale if two pounds of refrigerant does not fill the
system.
PRESSURE
SWITCH
SCHRADER
VALVE FITTING
CHARGING
STAND
REFRIGERANT
R12
CAPILLARY
COIL
EXPANSION
VALVE
RECEIVER
DEHYDRATOR
SIGHT GLASS
CONTAINER OF
WARM WATER
(125°F)
THIS END OF HOSE
MUST HAVE DEVICE
TO DEPRESS
SCHRADER VALVE
OPTIONAL METHOD
PREFERRED
METHOD
HP
SCALE
LP
CONDENSER
DISCHARGE LINE
SUCTION LINE
COMPRESSOR
EVAPORATOR
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
2 1 - 5 2 - 0 9
Page 21-66
Revised: May 15, 1989
1H9
PIPER AIRCRAFT