Using The Airplane Compressor To Charge The System - Piper Dakota Maintenance Manual

5. Connect heating element plug (16) to 110 volt outlet.
6. Turn cylinder sight glass to match pressure reading on cylinder pressure gauge, use this scale during
entire charging operation.
7. Close valve (3) (low pressure control), fully open valve (11) (refrigerant control) and allow all liquid
refrigerant contained in charging cylinder to enter high side of aircraft system.
8. When full charge of refrigerant has entered system, close valve (11) (refrigerant control) and valve
(10) (high pressure control).
9. After completion of charging, close all valves on charging stand, Disconnect high and low pressure
charging lines from aircraft system, (A small amount of refrigerant remaining in the lines will escape,)
Replace lines on holder of charging stand to keep air and dirt out of lines. Open valve at top of
cylinder to relieve any remaining pressure, then reclose valve.
10. Reinstall protective caps of Schrader valves and any access panels previously removed.

USING THE AIRPLANE COMPRESSOR TO CHARGE THE SYSTEM

This method is not desirable because it requires operating the airplane's engine to run compressor.
Ensure that area around airplane is clear and a qualified person
is at controls of airplane.
l. With system evacuated as outlined in Evacuating System, connect refrigerant charging hose to
manifold (refer to figure 21-9) and purge charging hose of air.
2. Place refrigerant container on a scale to observe amount of refrigerant entering system. Open high
pressure valve and add as much refrigerant as possible.
3. Close high pressure valve, start engine and operate it at 900 to 1000 rpm.
4. Operate air conditioner and set controls to maximum cooling.
5. Open low pressure valve and complete charging system.
6. Close low pressure valve after two pounds of refrigerant has been added to system.
7. With system still operating, observe sight glass in top of receiver-dehydrator by removing plastic plug.
8. Sight glass should be clear of any bubbles or foam. If bubbles or foam are seen passing through, it is
an indication of a low refrigerant charge in system and more refrigerant is required. This check should
be made with oat of 70° F or higher and with air conditioner operating.
9. If more refrigerant must be added, open low pressure valve and increase engine speed to 2000 rpm and
observe sight glass. After sight glass has cleared, close low pressure valve and observe pressure
gauges. At 1000 rpm the gauge pressure should be 15 to 20 psi on low side and 150 to 200 on high
side.
Suspect leaks or an inaccurate scale if two pounds of refrigerant
does not fill system
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
—WARNING—
—NOTE—
1G13
21 - 52 - 00
Page - 21 - 23
Reissued: August 1, 1986