PIPER SENECA II SERVICE
MANUAL
14-93.
AIR
CONDITIONING
INSTALLATION.
14-94.
DESCRIPTION.
This installation consists
of
a
compressor
with its special bracketry.
an
evaporator.
a
condenser,
a receiver-dehydrator. circulating fan. thermal
expansion
valve.
and
related plumbing.
The
evaporator
filters. dehumidifies
and
cools the air.
The
evaporator
is
mounted
in a fabricated housing
along
with the receiver-dehydrator, circulating fan, thermal
expansion
valve and related plumbing. This hous-
ing is located
at
the
rear
of
the
cabin. aft
of
the
baggage area. The
compressor
is
a piston type unit which
is
supported
by special bracketry
at
the
rear
of
the
engine.
AV-belt
connection drives the
compressor
through
a
magnetic
clutch. (Refer
to
Figure 14-24.)
The
condenser
is
installed in the left nacelle aft
of
the firewall. be-
tween
stations
78.00
and
98.00.
The
condenser
scoop
is
mounted
to allow extension into the
airstream
during
system
operation
and
is electrically activated.
The
system is protected by a pressure switch which
automatically
controls
the
condenser
maximum
head
pressures
by
temporarily de-clutching the
compressor
in the event the pressure becomes excessively high.
Controls
for
operating
the
air
conditioning system
are
located on the
instrument
panel
just
to
the right
of
the
copilot's
control
column.
Two
switches,
an
air
condition
ON-OFF
control
and
three position
(LOW-OFF-
HIGH) fan switch,
and
a radial
thermostat
make
up
the controls.
The
system design
is
such
that
there
is
no
increase in
drag
to the aircraft
during
its take-off flight condi-
tions.
During
maximum
power
demands
the
compressor
is
de-clutched
and
the
condenser
door
is
auto-
matically retracted.
14-95.
AIR
CONDITIONING
SYSTEM
OPERATION.
The
air
conditioning system in this airplane
is
a
recirculating,
independent
unit. It filters, dehumidifies
and
cools the
air
as
it
cycles
through
the
evaporator.
From
the
controls
as previously described, the system can be
operated
in two ways. (Refer to schematic Figure
11-49.)
The
fan (blower) switch, being the main
power
control
switch
to
the system. can
he
operated solely to
provide
circulation
at
high
or
low blower,
or
in
conjunction
with the
air
conditioning
ON-OFF
switch. provide
air
conditioning
at high
or
low blower. It
is
important
to
note
that
the
"FAN"
switch must be in low
or
high
to
provide
power
to
the
"Air
Conditioning
ON-OFF"
switch
and
the rest
of
the
system. A
thermostatic
switch
is also provided
to
control
temperature.
The
air
conditioning
system uses Refrigerant
12
as
the
refrigerant.
The
refrigerant enters the
compressor
as a
vapor.
The
compressor
pressurizes the heat-laden
vapor
until its pressure
and
heat reach a point much
hotter
than
the
outside air.
The
compressor
then
pumps
the
vapor
to
the
condenser
where it cools and changes
to
a liquid.
The
liquid
then
passes
to
the
receiver-dehydrator. Its function
is
to filter. remove any moisture
and
insure a steady flow
of
liquid refrigerant
into
the
evaporator
through
the
expansion
\alve.
The
expansion
valve is a
temperature
controlled metering valve which regulates
the
flow
of
the liquid refrigerant to the evap-
orator.
The
evaporator
absorbs
the heat from the
air
passing over the coils.
From
the
evaporator
the re-
frigerant
vapor
returns
to
the
compressor
where
the
cycle
is
repeated.
Revised:
8/10/80
NOTE
A table
at
the end
of
these instructions will assist in locating and
correcting
malfunctions which may arise in this system.
ACCESSORIES
AND
UTILITIES
3C23
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