Refrigerant Drum Method; Discharging The System; Evacuating The System Using External Vacuum Pump; Evacuating The System Using System Compressor - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
CAUTION
Tipping the container and allowing liquid refrigerant to enter the
system can damage the compressor. Continue to add refrigerant
until the sight glass clears of all bubbles. Close the container valve
after the sight glass clears.
6.
If means are available to weigh the container, an additional 1/2 pound of refrigerant can be
added to increase the time between system charges.
7. Turn off the air conditioner and stop the engine after charging. Remove the charging hose
from the Schrader valve using a cloth to direct the escaping refrigerant. Recap Schrader valve.
14-102. REFRIGERANT
DRUM METHOD.
a. DISCHARGING THE SYSTEM.
1. Close both valves on a standard gauge set. Connect the red high pressure hose from the gauge set
to the high pressure Schrader valve on the fire wall fitting. Connect the blue low pressure hose from the gauge
set to the low pressure Schrader valve on the fire wall fitting. (Refer to Figures 14-38 and 14-42.)
2.
Crack both valves on the gauge set and allow the system to slowly discharge. Regulate flow
to prevent oil loss from the compressor during discharging.
3. Close valves on gauge set after system is discharged.
b.
EVACUATING THE SYSTEM USING EXTERNAL VACUUM PUMP.
1. With gauge set connected per paragraph a and gauge valves open, connect the suction line of
the vacuum pump to the center outlet of the gauge set.
2. Start vacuum pump and pull a vacuum of 26 to 28 inches mercury. Continue to operate
pump for 25 minutes.
3. If 26 to 28 inches vacuum cannot be attained, check system for leaks per paragraph c.
NOTE
Reduce vacuum reading one inch for each 1000 feet altitude above
sea level.
4. After evacuating, check for leaks per paragraph d.
5. When no leaks are evident close service valves on compressor, remove gauge set and proceed
with charging per paragraph e.
c.
EVACUATING SYSTEM USING SYSTEM COMPRESSOR.
NOTE
This method is the least desirable due to the requirement of
working near the running engine.
1. Using lines long enough to extend from the rear of the wing, connect the gauge set to the fire wall
fitting Schrader valves. Connect the low pressure gauge to the suction side and the high pressure gauge to the
discharge side. (Refer to Figures 14-38 and 14-42.) Secure the gauge set to prevent movement and aircraft
damage from prop blast.
2.
Open the high pressure gauge valve fully. Close the low pressure gauge valve.
Reissued: 9/23/80
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ACCESSORIES AND UTILITIES
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