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COMPRESSOR OVERLOAD — This overload interrupts
power to the compressor when either the current or
internal motor winding temperature becomes excessive,
and automatically resets when the internal temperature
drops to a safe level. This overload may require up to 60
minutes (or longer) to reset. If the internal overload is
suspected of being open, disconnect the electrical power
to the unit and check the circuit through the overload with
an ohmmeter or continuity tester.
ADVANCED SCROLL TEMPERATURE PROTECTION
(ASTP) — A label located above the terminal box identifies
Copeland Scroll compressor models that contain this
technology. See Fig. 14. Advanced Scroll Temperature
Protection (ASTP) is a form of internal discharge
temperature protection, that unloads the scroll compressor
when the internal temperature reaches approximately 149_C
(300_F). At this temperature, an internal bi- - metal disk valve
opens and causes the scroll elements to
stops compression. Suction and discharge pressures balance
while the motor continues to run. The longer the compressor
runs unloaded, the longer it must cool before the bi- - metal
disk resets. See Fig. 15.
Fig. 14 - - Advanced Scroll Temperature Protection Label
120
110
100
90
80
70
60
50
40
30
20
10
0
0
10
20
30
Compressor Unloaded Run Time (Minutes)*
*Times are approximate.
NOTE: Various factors, including high humidity, high ambient
temperature, and the presence of a sound blanket will
increase cool-down times.
Fig. 15 - - Recommended Minimum Cool-Down Time
After Compressor is Stopped
separate, which
C10080
40
50
60
70
80
90
C10081
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 automatically before the
motor protector resets, which may take up to 2 hours.
START UNIT — Set the space thermostat to a set point
above space temperature so that there is no demand for
cooling. Close the 38AUD disconnect switch. Only the
crankcase heater will be energized.
Reset the space thermostat below ambient so that a call
for cooling is ensured.
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Never charge liquid into the low-pressure side of
system. Do not overcharge. During charging or
removal of refrigerant, be sure indoor-fan system is
operating. Ensure both outdoor fan motors are
running; bypass any Motormaster function.
ADJUST REFRIGERANT CHARGE — Refer to Cooling
Charging Charts, Fig. 16 and Fig. 17. For applications
with line lengths greater than 38m (125 ft), contact Carrier
representative. Vary refrigerant until the conditions of the
chart are met. Note that the charging charts are different
from the type normally used. The charts are based on
charging the units to the correct subcooling for the various
operating conditions.
Accurate pressure
temperature sensing device are required. Connect the
pressure gage to the service port on the liquid line service
valve. Mount the temperature sensing device on the liquid
line close to the liquid line service valve, and insulate it so
that outdoor ambient temperature does not affect the
reading. Indoor airflow must be within the unit's normal
operating range. Operate the unit for a minimum of 15
minutes. Ensure that pressure and temperature readings
have stabilized. Plot the liquid pressure and temperature
on chart and add or reduce the charge to meet the curve.
Adjust the charge to conform with the charging chart,
using the liquid pressure and temperature to read the
chart.
FINAL CHECKS — Ensure that all safety controls are
operating, control panel covers are on, and the service
panels are in place.
18
gage and
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