Installation guide
A.
UNITS
WITH
COOLING
MODE
TXV
Units
installed
with
cooling
mode
TXV
require
charging
by
the
subcooling
method.
1.
Operate
unit
a
minimum
of
15
minutes
before
checking
charge.
NOTE:
If
outdoor
unit
has
a
2-speed
fan
motor,
motor
will
operate
in
low
speed
when
outdoor
ambient
temperature
is
below
82°F
(28°C).
Pull
the
BRN/YEL
low
voltage
wire
off
the fan
control
and
the
unit
will
default
to
high
speed
fan
for
servicing.
Reconnect
wire
after
servicing.
Measure
liquid
service
valve
pressure
by
attaching
an
accurate
gage
to
service
port.
Measure
liquid
line
temperature
by
attaching
an
accurate
thermistor
type
or
—
electronic
thermometer
to
liquid
line
near
outdoor
coil.
Refer
to
unit
rating
plate
for
required
subcooling
temperature.
Refer
to
Figure
16.
Find
the
point
where
required
subcooling
temperature
intersects
measured
liquid
service
valve
pressure.
To
obtain
required
subcooling
temperature
at
a
specific
liquid
line
pressure,
add
refrigerant
if
liquid
line
temperature
is
higher
than
indicated
or
reclaim
refrigerant
if
temperature
is
lower.
Allow
a
tolerance
of
+3°F
(+1.7°C).
B.
UNITS
WITH
INDOOR
PISTON
Units
installed
with
indoor
pistons
require
charging
by
the
superheat
method.
The
following
procedure
is
valid
when
indoor
airflow
is
within
+21
percent
of
its
rated
CFM.
1.
2.
10.
11.
12.
Operate
unit
a
minimum
of
15
minutes
before
checking
charge.
Measure
suction
pressure
by
attaching
an
accurate
gage
to
suction valve
service
port.
Measure
suction
temperature
by
attaching
an
accurate
thermistor
type
or
—
electronic
thermometer
to
suction
line
at
service
valve.
Measure
outdoor
air
dry-bulb
temperature
with
thermometer.
Measure
indoor
air
(entering
indoor
coil}
wet-bulb
temperature
with
a
sling
psychrometer.
Refer
to
Figure
14.
Find
outdoor
temperature
and
evaporator
entering
air
wet-bulb
temperature.
At
this
intersection,
note
superheat.
Where
a
dash
(--)
appears
on
the
table,
do
not
attempt
to
charge
system
under
these
conditions
or
refrigerant
slugging
may
occur.
Charge
must
be
weighted
in,
adding
or
removing
0.6
o2/ft
of
3/8
liquid
line
above
or
below
15
feet
(4.6m)
respectively.
Refer
to
Figure
15.
Find
superheat
temperature
(from
#6
above)
and
suction
pressure.
At
this
intersection,
note
suction
line
temperature.
If
unit
has
a
higher suction
line
temperature
than
charted
temperature,
add
refrigerant
until
charted
temperature
is
reached.
If
unit
has
a
lower
suction
line
temperature
than
charted
temperature,
reclaim
refrigerant
until
charted
temperature
is
reached.
When
adding
refrigerant,
charge
in
liquid
form
into
suction
service
port
using
a_
flow-restricting
device.
If
outdoor
air
temperature
or
pressure
at
suction
valve
changes,
charge
to
new
suction
line
temperature
indicated
on
chart.
Optimum
performance
will
be
achieved
when
the
operating
charge
produces
5°
to
6°F
suction
superheat
at
suction
service
valve
with
82°F
(28°C)
outdoor
ambient
and
80°F
(27°C)
dry
bulb
(67°F
/
19°C)
wet
bulb)
indoor
temperature
(DOE
“B”
test
conditions)
at
rated
airflow.
428
01
5103
02
15