Diagnosis
155
Head pressure too low
NOTE: This unit has a
suction modulation
capacity control system.
Suction and discharge
pressures may drop below
expected normal readings
when the unit is in
Modulation Cool (control
temperature within 10 C
[18 F] of setpoint or in
Power Limit mode).
Shortage of refrigerant
Repair leak and recharge
Low ambient air temperature
No remedy
Service gauge out of calibration
Replace gauge
Compressor suction or discharge
valve inefficient
Clean or replace leaking valve plates
Head pressure too high
Refrigerant overcharge
Purge system
Air in refrigeration system
Evacuate and recharge
Dirty or restricted condenser coil
Clean condenser coil
Condenser fan not operating
See “Condenser fan motor does not
operate” under Mechanical Diagnosis
Condenser fan grille damaged or
missing
Repair or replace grille
Condenser fan blade damaged
Replace fan blade
High ambient air temperature
No remedy
Restricted filter drier or high side
Replace filter drier or clear restriction
Defective high pressure gauge
Replace service gauge
Compressor loses oil
Refrigerant leak
Repair leak and recharge
Compressor oil migrates to
system
Short cycling
See “Unit short cycles” under
Mechanical Diagnosis”
Rapid cycling between Cool
and Heat modes
Air short cycling through evaporator
Check and correct cargo load
Defective controller or main relay
board
Diagnose main relay board and
controller. Replace defective component
Short Cycling
See “Unit short cycles” under
Mechanical Diagnosis
Evaporator pressure regulator (KVQ)
valve stuck closed or defective
Repair or replace valve
Hot liquid line
Shortage of refrigerant
Repair or recharge
Expansion valve open too wide
Adjust or replace expansion valve
Frosted liquid line
Liquid line service valve partially
closed or restricted
Open valve or remove restriction
Restricted filter drier
Replace filter drier
Condition
Possible Cause
Remedy
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...