Operating Instructions
46
Other Unit Controls
1. EVAPORATOR OVERHEAT SWITCH. A
temperature switch near the evaporator coil
opens to de-energize the heater contactor if the
evaporator temperature reaches 54 C (130 F).
The switch closes (resets) when the evaporator
temperature decreases to 32 C (90 F).
Unit Instruments
1. RECEIVER TANK SIGHT GLASS. A sight
glass on the receiver tank contains three small
balls that indicate the level of refrigerant in
the tank for checking the refrigerant charge. A
moisture indicator in the sight glass changes
color to indicate the level of moisture in the
system. Check the color of the indicator
against the color decal in the sight glass. The
dry eye in the sight glass is LIGHT GREEN
when the system is dry and YELLOW when
the system is wet (contains excessive
moisture).
2. COMPRESSOR OIL SIGHT GLASS. A
compressor oil sight glass indicates the
relative level of compressor oil in the
compressor sump.
3. SUCTION PRESSURE GAUGE. A suction
pressure gauge indicates the refrigerant
pressure in the suction line returning to the
compressor.
4. DISCHARGE PRESSURE GAUGE. A
discharge pressure gauge indicates the
refrigerant pressure in the discharge line
leaving the compressor.
Unit Protection Devices
1. MAIN CIRCUIT BREAKER. A 25 ampere
manual reset circuit breaker protects the
460/380V power supply circuit to the unit
electric motors and control system
transformer. The main power circuit breaker is
located in the control box.
2. CONTROL SYSTEM CIRCUIT BREAKER.
A 7 ampere manual reset circuit breaker or a 7
ampere ATO fuse protects the 29 Vac control
circuit. This circuit breaker is located in the
control box beside the On/Off switch. The
ATO Fuse is located inside the control box on
the right side wall.
3. FUSES. A number of fuses are located on the
main relay board and controller to protect unit
circuits and components.
•
Three 20 amp fuses protect high voltage
circuits on the main relay board.
•
A 2 amp fuse protects the controller’s 28
V system.
•
A 2 amp fuse protects the controller’s
battery charging circuit.
4. COMPRESSOR DISCHARGE LINE
TEMPERATURE SENSOR. The controller
uses the compressor discharge line
temperature sensor to protect the compressor
from excessively high operating temperatures
and activate liquid injection during Chill mode
(setpoints at -9.9 C [10.1 F] and above).
•
High Temperature Protection: If the
discharge gas temperature rises above 130
C (266 F), the unit stops immediately. The
controller turns ON the Alarm LED and
records Alarm 56, Compressor
Temperature Too High. The controller will
restart the unit when the sensor
temperature is below 90 C (194 F).
1.
Moisture Indicator:
Light Green = Dry or Yellow = Wet
2.
Outer ring is color coded. Compare to indicator
Figure 12: Receiver Tank Sight Glass
1
2
AJA1412
Summary of Contents for CRR-40 119
Page 4: ......
Page 16: ...Safety Precautions 16...
Page 18: ...Service Guide 18...
Page 20: ...Model Features 20...
Page 32: ...Specifications 32...
Page 120: ...MP 3000a Controller 120...
Page 160: ...Wiring and Schematic Diagrams Index 160...
Page 161: ...161 MPC2000 Wiring Schematic...
Page 162: ...162 MPC2000 High Voltage Wiring Diagram...
Page 163: ...163 MPC2000 Low Voltage Wiring Diagram...
Page 164: ...164 MPC2000 WCC Wiring Schematic...