24
ADVANCED SCROLL TEMPERATURE PROTECTION
(ASTP)
A label located above the terminal box identifies Copeland
1
Scroll compressor models that contain this technology. See
Fig. 23. 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
separate, which stops compression. Suction and discharge pres-
sures 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. 24.
To manually reset ASTP, the compressor should be stopped
and allowed to cool. If the compressor is not stopped, the mo-
tor 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.
Fig. 23 — Advanced Scroll Temperature Protection
Label
Fig. 24 — Recommended Minimum Cool-Down Time
After Compressor is Stopped
Start Unit
Set the space thermostat to a set point above space tempera-
ture so that there is no demand for cooling. Close the 38AU dis-
connect switch. Only the crankcase heater will be energized.
Reset the space thermostat below ambient so that a call for
cooling is ensured.
ADJUST REFRIGERANT CHARGE
Refer to Cooling Charging Charts, Fig. 25-32. For applica-
tions with line lengths greater than 125 ft (38 m), 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 gage and temperature sensing device are required. Con-
nect the pressure gage to the service port on the liquid line ser-
vice 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. Oper-
ate 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. see Table 17. Adjust the charge to conform with the
charging chart, using the liquid pressure and temperature to read
the chart.
Table 17 — Using Plotted Operating Point:
FINAL CHECKS
Ensure that all safety controls are operating, control panel
covers are on, and the service panels are in place.
1. Copeland is a trademark of Emerson Climate Technologies.
0
10
20
30
40
50
60
70
80
90
100
110
120
0
10
20
30
40
60
70
80
90
50
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.
Recommended Cooling
T
ime*
(Minutes)
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment dam-
age.
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.
IF PLOTTED OPERATING
CONDITION IS
ADJUST CHARGE BY
BELOW the curve
REDUCE charge
ABOVE the curve
ADD charge
Summary of Contents for Gemini 38AU07 Series
Page 5: ...5 Fig 3 38AUD Z 07 14 Base Unit Dimensions ...
Page 19: ...19 Fig 17 Typical Single Circuit Single Stage 38AUZ Wiring Diagrams ...
Page 20: ...20 Fig 18 Typical Single Circuit Two Stage 38AUZ Wiring Diagram ...
Page 21: ...21 Fig 19 Typical Dual Circuit Two Stage 38AUD Wiring Diagram ...
Page 30: ...30 Fig 30 38AUZD E08 Charging Chart RTPF 7 5 Ton Dual Stage Charging Chart R 410A Refrigerant ...
Page 48: ......
Page 49: ......
