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III. START UP COOLING SECTION AND MAKE
ADJUSTMENTS
A superheat
charging
label
is attached
to the
inside
of the
compressor
access
door. The label
includes
a "Superheat
Charg-
ing
Table"
and
a "Required
Suction-Tube
(F) Temperature"
chart.
An accurate
superheat,
thermocouple,
or thermistor
type ther
monmter,
a sling
psychrometer,
and
a gage
manifold
are
re
quired
when
using
the
superheat
charging
method
for evalu
ating
the
unit
charge.
Do not u,se me['c'rHy
or small
Hial-(ype
themlome_ers
bec'ouse
they ore not oclequa_e
_bz" this
_ype
of
measzmemenb
A. Checking
Cooling
Control
Operation
Start
and
check
the
unit
for" proper
cooling
control
operation
as follows:
1. Place
room thermostat
SYSTEM
switch
in OFF posL
tion. Observe
that blower motor starts
when FAN switch
is placed in ON position and shuts down when FAN switch
is placed
in AUTO,
position.
2. Place SYSTEM
switch in COOL position and FAN switch
in AUTO. position.
Set cooling control
below room tem-
perature.
Obsexwe that compressor,
condenser
fan, and
evaporator
blower
motors
start.
Observe
that
cooling
cycle shuts
down when
control
setting
is satisfied.
The
evaporator
fan will continue
to run for" 30 seconds.
3. When using an auto. changeover
room thermostat,
place
both
SYSTEM
and FAN switches
in AUTO. positions.
Observe
that unit
operates
in heating
mode when tern
perature
control
is set to "call for heating"
(above room
temperature)
and operates
in cooling mode when
tem-
perature
control is set to "call for" cooling"
(below room
temperature).
IMPORTANT:
Three
phase,
scroll
compressor
units
(sizes
048,060) are direction-oriented.
These units
must
be checked
to ensure
proper
compressor
3-phase
power lead orientation.
If not corrected
within
5 minutes,
the internal
protector
will
shut off the compressor.
The 3 phase
power leads to the unit
must
be reversed
to correct
rotation.
When
turning
back
wards,
scroll compressors
emit elevated
noise levels, and the
difference
between
compressor
suction
and
discharge
pres-
sures
may be dramatically
lower than normal.
B. Checking and Adjustment
Refrigerant Charge
The refrigerant
system
is fully charged
with
R-22 refriger-
ant, tested,
and factory sealed.
NOTE: Adjustment
of the refl'igerant
charge
is not required
unless
the unit
is suspected
of not having
the proper" R-22
charge.
Proceed
as follows:
1. Remove
caps
fl'om
low
and
high pressure
service
fittings.
2. Using hoses with valve core depressors,
attach
low- and
high-pressure
gage hoses to low- and high-pressure
serw
ice fittings,
respectively.
3. Start
unit in cooling mode and let unit run until system
pressures
stabilize.
4. Measure
and record the following:
a. Outdoor
ambient
air temperature
(F db).
b. Evaporator
inlet-air
temperature
(F wb).
c. Suction
tube
temperature
(F) at
low side
service
fitting.
d. Suction
(low-side)
pressure
(psig).
5. Using
"Superheat
Charging
Table,"
compare
the out-
door entering
air temperature
with indoor air tempera-
rare
to determine
desired
system
operating
superheat
temperature.
See Tables
7A 7H.
6. Using
"Required
Suction-Tube
(F) Temperature"
table,
compare desired superheat
temperature
with suction (lmw
side) operating
pressure
(psig) to determine
proper suction-
tube temperature.
See Table 8.
7. Compare
actual
suction-tube
temperature
with proper
suction-tube
temperature.
Using a tolerance
of _+3 ° F,
add refl'igerant
if actual
temperature
is more than
3 ° F
higher
than
proper
suction
tube
temperature,
or re
move refrigerant
if actual
temperature
is more
than
3 ° F lower than required
suction-tube
temperature.
NOTE:
If the problem
causing
the inaccurate
readings
is a
refl'igerant
leak, refer to Check for" Refl'igerant
Leaks section
on page 16.
2O
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