Charging The Sytem - Full Charge; Compressor Oil Level Check - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
3.
Start the right engine and run at 900-1000 prop rpm. Turn air conditioner on in manual
mode.
4. Evacuate to 26 to 28 inches vacuum. Continue to evacuate system for approximately 10
minutes. Close the high pressure gauge valve. Turn off the air conditioner and stop the right engine. Check
the system for leaks per paragraph d.
5. If you cannot pull 26 to 28 inches (at sea level) vacuum on the system, turn off air
conditioner and engine. Check for leaks per paragraph d.
NOTE
Decrease vacuum reading one inch for each 1000 feet of elevation
above sea level.
6. When no leaks are evident charge per paragraph e.
d.
CHECKING SYSTEM FOR LEAKS.
1. With the gauge set hoses connected per paragraph a and system evacuated, connect a
charging hose between the gauge set manifold and a refrigerant container.
2.
The refrigerant container should be placed in a container of warm (150
°
F max.) water. The
container should be in the upright position with the valve on top.
3.
Open the refrigerant container valve with the gauge set high pressure valve open and allow
refrigerant gas to enter the system until the system pressure stops rising. Close the container valve.
4. Using the Bacharack Leakator or equivalent electronic leak detector, check all joints and
repair any leaks.
5. Release the refrigerant, evacuate the system again for approximately 15 minutes and then
add another refrigerant gas charge per line 3 above.
6. Release the refrigerant and again evacuate the system for 5 minutes to be sure all
contamination is removed. The system is now ready for charging.
e. CHARGING THE SYSTEM - FULL CHARGE.
1. Determine the weight of the refrigerant container and its heating water and container on a
suitable scale. The refrigerant container and scale should be located at the rear of the wing or on the left
side of the fuselage well clear of the right prop.
2.
Loosely connect a suitable charging line to the gauge set which should be connected to the
evacuated system. Connect the other end of the charging line to the refrigerant container valve and purge
the line by opening the valve and allowing refrigerant gas to flow through the hoses. Tighten the hose at the
gauge set, open the low pressure gauge valve.
3. With the right engine operating at 900-1000 rpm and the air conditioner ON, allow 4
pounds of refrigerant gas to flow into the system by opening the container valve. Close the container valve
when the proper charge is reached and stop.
4.
Carefully remove the gauge set hoses from the fire wall fitting Schrader valves. Use a cloth
to divert any escaping refrigerant. Recap the Schrader valves.
e. ADDITION OF PARTIAL CHARGE. (See Paragraph 14-101, f.)
14-103. COMPRESSOR OIL LEVEL CHECK. (Refer to Figure 14-39.)
a. Anytime the air conditioning system is discharged, the oil level in the compressor should be checked.
The dipstick required for this check is shown in Figure 14-39.
The following dipstick calibration applies with the compressor installed on the aircraft:
Reissued: 9/23/80
ACCESSORIES AND UTILITIES
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