PIPER
SENECA
II
SERVICE
MANUAL
14-102. LEAK CHECK - METHOD II.
a. Remove the access panel at the rear
of
the cabin to gain access
to
the service valves.
b. Remove the protective cap on the high pressure Schrader
valve
fitting and connect a charging
hose with a shut-off valve arrangement to the fitting. The charging hose must have a Schrader fitting or
adapter
to
fit the valve.
c.
Connect the other end
of
the charging hose
to
a small cylinder
of
refrigerant and purge the hose
by allowing a slight amount
of
refrigerant
gas
to
escape from the Schrader
valve
fitting.
d.
The cylinder of refrigerant should
be
placed upright
in
a container of warm (
125°
F max.) water off
a small scale.
e. Allow approximately 1 /2 pound
of
refrigerant
to
enter the system by opening the
valve
on the
charging hose and observing the weight change on the scale.
f.
Using
an
electronic leak detector, check all joints and repair any leaks.
g.
After completion
of
repair
of
any leaks, proceed
to
check the system in accordance with one
of
the methods outlined for any other leaks.
h.
If
no
further repair
is
required on the system,
it
is
now ready to evacuate in accordance with
Paragraph 14-104.
14-103. DISCHARGING.(Required only if system contains refrigerant.)
NOTE
Applies to Kent Moore
J23500
or
similar charging station. Refer
to
Figure
14-29.
a.
Close
all
valves on charging station.
b.
Connect red high pressure charging line
to
high pressure Schrader
valve
at the evaporator fitting.
c. Open
valve
8 (high pressure control) on charging station one
tum.
d. Hold end
of
blue low pressure charging line in a shop rag and slowly open
valve
2 (low pressure
control) on charging station allowing refrigerant
to
exhaust from system into shop
rag.
CAUTION
Refrigerant can cause freezing
of
skin.
Be
particularly careful not
to
allow contact with the eyes.
Do
not
allow refrigerant to escape
too
rapidly,
as
excessive oil may
be carried
out
of
system.
When
hissing stops, system is empty and
valve should be closed
if
no further work
is
planned.
14-104. EVACUATING
THE
SYSTEM.If
the system has been operated in a discharged condition or
anytime the system has been open to atmospheric pressure, the receiver-dehydrator must be replaced and
the system evacuated to remove any trapped air and moisture which has entered it. A vacuum pump
capable
of
pulling 29 inches
of
mercury
or
better should be used.
As
we
lower the pressure in the air
conditioning system,
we
lower the boiling temperature
of
the water (moisture) that may be present. Then
we
are able to pull this water, in the form
of
vapor,
out
of
the system. The following table demonstrates the
effectiveness
of
moisture removal under a given vacuum.
Reissued:
10/11/79
3D8
ACCESSORIES
AND
UTILITIES
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