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LEFT
ADJUSTMENT
SCREW
(HIDDEN)
LEFT
BYPASS
CAP
Fig. 96 — Modulating Gas Valve Bypass
Adjustment
MAIN BURNERS
For all applications, main burners are factory set and should re-
quire no adjustment.
MAIN BURNER REMOVAL AND REPLACEMENT
1.
Shut off (field-supplied) manual main gas valve.
2.
Shut off power to unit.
3.
Remove gas section access door, door frame, and corner post.
4.
Disconnect gas piping from gas valve inlet.
5.
Remove wires from gas valve.
6.
Remove wires from rollout switch.
7.
Remove sensor wire and igniter cable form IGC board.
8.
Remove 2 screws securing manifold bracket to basepan.
9.
Remove 2 screws that hold the burner support plate flange
to the vestibule plate.
10. Lift burner assembly out of unit.
11. Replace burner assembly. Reinstall by reversing Steps 1
to 10.
Moisture/Liquid Indicator
A clear flow of liquid refrigerant indicates sufficient charge in the
system. Bubbles indicate undercharged system or the presence of
noncondensables. Moisture in the system measured in parts per
million
(ppm)
changes
Green
—
moisture
Chartreuse
—
45
Yellow — moisture above 130 ppm (wet)
Change filter driers at the first sign of moisture in the system. See
Carrier Charging Handbook for more information.
IMPORTANT: Unit must be in operation at least 12 hours
before moisture indicator can give an accurate reading. With unit
running, indicating element must be in contact with liquid refrig-
erant to give a true reading.
TERMINALS
RIGHT
ADJUSTMENT
SCREW
(HIDDEN)
RIGHT
BYPASS
CAP
the
color
of
the
indicator.
below
45
ppm
to
130
ppm
(caution!)
Filter Drier
Replace whenever the moisture/liquid indicator shows moisture in
the system.
Liquid Line Service Valves
Use caution when closing liquid line service valves. The expan-
sion of a trapped liquid can create dangerously high pressures. Re-
move refrigerant immediately from trapped sections or attach a
hose from the high side to the low side of the system to provide re-
lief. If equipped with a liquid line solenoid valve in the evaporator
section, it will be closed during the off-cycle. This creates the po-
tential for a liquid trap between the solenoid valve and a closed
service valve. Remove refrigerant immediately from the section or
attach a hose for relief.
Protective Devices
COMPRESSOR PROTECTION
Overcurrent
Each compressor has one manual reset, calibrated trip, magnetic
circuit breaker. Do not bypass connections or increase the size of
the circuit breaker to correct trouble. Determine the cause and cor-
rect it before resetting the breaker.
Overtemperature
Each compressor has a protector to protect it against excessively
high discharge gas temperatures.
Additionally, some units contain Copeland compressors equipped
with advanced scroll temperature protection (ASTP). A label lo-
cated above the terminal box identifies Copeland Scroll compres-
sor models that contain this technology. See Fig. 97. Advanced
scroll temperature protection is a form of internal discharge tem-
perature protection that unloads the scroll compressor when the in-
ternal temperature reaches approximately 300°F. At this tempera-
ture, an internal bi-metal disk valve opens and causes the scroll el-
ements to separate, which stops compression. Suction and
discharge pressures balance while the motor continues to run. The
longer the compressor runs unloaded, the longer it must cool be-
fore the bi-metal disk resets. See Fig. 98.
To manually reset ASTP, the compressor should be stopped and
allowed to cool. If the compressor is not stopped, the motor will
run until the motor protector trips, which occurs up to 90 minutes
later. Advanced scroll temperature protection will reset automati-
cally before the motor protector resets, which may take up to
2 hours.
(dry)
Fig. 97 — Advanced Scroll Temperature
184
Protection Label
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Troubleshooting
