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MP-3000a Controller
116
Code
Description
Corrective Action
52
Probe Error (Check Alarm)
• Occurs during Pretrip (PTI) test or Probe Test
failed in CHilled mode
• Temperature difference between return air and
evaporator coil sensors is too high (1.5 C [2.7 F]
difference maximum)
• Temperature difference between return air and
supply air sensors is too high (0.8 C[1.5 F]
difference maximum)
• Temperature difference between LH supply and
RD supply sensors is too high (0.5 C [1.0 F]
difference maximum)
• Indicates:
• Incorrect temperature reading on one sensor
• Supply air sensor not placed in air flow stream
• Check sensor connections. Check sensor
resistance of each sensor. Resistance must be
2,000 ohms at 25 C (77 F).
• Check left hand and right hand supply air sensor
locations.
NOTE: Code 52 has been replaced by codes 115, 116, 117 in the current revision of the controller
software. If code 52 appears on the controller screen, the controller software is not current and needs
to be updated.
53
High Pressure Cutout Switch Off Error (Check
Alarm)
• Occurs during Pretrip (PTI) test only.
• Compressor does not stop during high pressure
cutout switch test.
• Indicates:
• Faulty compressor contactor or control circuit
• Low refrigerant charge
• Defective high pressure cutout switch
• Strong winds causing cooling of condenser
coil in low ambient conditions
• Check discharge and suction pressure gauge
readings and check refrigerant charge.
• Enter Manual Function Test menu. Start the
following components together: compressor
100%, compressor and evaporator fans (high).
Discharge pressure should increase and
compressor should stop at 2250 kPa, 22.5 bar,
326 psig (high pressure cutout switch opens).
54
High Pressure Cutout Switch On Error (Check
Alarm)
• Occurs during Pretrip (PTI) test only.
• Compressor does not start within normal time
during high pressure cutout switch test.
• Indicates:
-High pressure cutout switch did not respond to
pressure change within 5 seconds
-Air in refrigeration system
-Defective high pressure cutout switch
• Check discharge and suction pressure gauge
readings.
• Enter Manual Function Test menu. Start the
following components together: compressor
100%, compressor and evaporator fans (high).
Discharge pressure should increase and
compressor should stop at 2250 kPa, 22.5 bar,
326 psig (high pressure cutout switch opens).
Then start condenser fan. Discharge pressure
must drop quickly (10 to 20 seconds) to 1550
kPa, 15.5 bar, 225 psig and compressor should
start (switch closes).
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...