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6.1Unit will not Start or Starts then Stops
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No power to unit
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External power source OFF
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Turn on
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Start-Stop switch (ST) OFF or defective
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Check
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Circuit breaker tripped or OFF
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Check
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Loss of control power
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Circuit breaker OFF or defective
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Check
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Control transformer defective
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Replace
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Fuse (F3 / F4) blown
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Check
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Start-Stop switch (ST) OFF or defective
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Check
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Component(s) not operating
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Evaporator fan motor internal protector open
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Section 7.6
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Condenser fan motor internal protector open
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Section 7.3
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Compressor internal protector open
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Section 7.2
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High Pressure Switch (HPS) open
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Section 6.7
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Heat Termination Thermostat (HTT) open
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Replace
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Current sensor malfunction
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Replace
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6.2Unit Operates Long or Continuously in Cooling
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Container
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Hot load
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Normal
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Box insulation defective or air leak
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Repair
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Refrigeration system
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Refrigerant shortage
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Section 7.1.6
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Evaporator coil covered with ice
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Section 6.6
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Evaporator coil plugged with debris
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Section 7.6
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Evaporator fan(s) rotating backwards
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Section 7.6
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Air bypass around evaporator coil
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Check
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Controller set too low
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Reset
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Compressor service valves or liquid line shutoff valve partially closed
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Open valves completely
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Condenser dirty
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Section 7.3
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Compressor worn
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Section 7.2
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Current limit (Cd32) set to wrong value
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See Cd32
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Electronic Expansion Valve (EEV)
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Replace
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6.3Unit Runs but has Insufficient Cooling
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Refrigeration system
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Abnormal pressures
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Section 6.7
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Abnormal temperatures
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Section 6.13
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Abnormal currents
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Section 6.14
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Controller malfunction
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Section 6.9
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Evaporator fan or motor defective
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Section 7.6
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Compressor service valves or liquid line shutoff valve partially closed
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Open valves completely
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Frost on coil
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Section 6.10
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Electronic Expansion Valve (EEV)
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Replace
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6.4Unit will not Heat or has Insufficient Heating
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No operation of any kind
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Start-Stop switch (ST) OFF or defective
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Check
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Circuit breaker OFF or defective
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Check
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External power source OFF
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Turn ON
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No control power
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Circuit breaker or fuse defective
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Replace
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Control transformer defective
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Replace
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Evaporator fan internal motor protector open
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Section 7.6
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Heat relay defective
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Check
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Heater termination thermostat open
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Unit will not heat or has insufficient heat
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Heater(s) defective
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Section 7.6
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Heater contactor or coil defective
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Replace
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Evaporator fan motor(s) defective or rotating backwards
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Section 7.6
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Evaporator fan motor contactor defective
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Replace
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Controller malfunction
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Section 6.9
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Wiring defective
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Replace
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Terminal connections loose
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Tighten
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Line voltage is low
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Section 3.10
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6.5Unit will not Terminate Heating
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Unit fails to stop heating
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Controller improperly set
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Reset
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Controller malfunction
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Section 6.9
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Heater Termination Thermostat (HTT) remains closed along with the heat relay
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6.6Unit will not Defrost Properly
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Will not initiate defrost automatically
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Defrost timer malfunction (Cd27)
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Link
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Terminal connections loose
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Tighten
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Wiring defective
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Replace
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Defrost Temperature Sensor (DTS) defective or Heat Termination Thermostat (HTT) open
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Replace
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Heater contactor or coil defective
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Replace
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Will not initiate defrost manually
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Manual defrost switch defective
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Replace
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Keypad defective
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Replace
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Defrost Temperature Sensor (DTS) open
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Replace
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Initiates but relay (DR) drops out
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Line voltage is low
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Section 3.10
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Initiates but does not defrost
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Heater contactor or coil defective
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Replace
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Heater(s) burned out
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Section 7.6
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Frequent defrost
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Load is wet
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Normal
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6.7Abnormal Pressures
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High discharge pressure
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Condenser coil dirty
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Section 7.3
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Condenser fan rotating backwards
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Section 7.3
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Condenser fan inoperative
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Section 7.3
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Refrigerant overcharge or non-condensibles
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Discharge service valve partially closed
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Open
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Electronic Expansion Valve (EEV) control malfunction
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Replace
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Low suction pressure
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Software and/or controller configuration incorrect
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Check
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Suction Pressure Transducer (SPT) or Evaporator Pressure Transducer (EPT) failed
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Replace
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Suction service valve partially closed
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Open
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Filter drier partially plugged
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Section 7.5
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Refrigerant charge low
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Evaporator air flow not existent or air flow restricted
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Section 7.6
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Frost on evaporator coil excessive
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Section 6.6
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Evaporator fan(s) rotating backwards
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Section 7.6
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Electronic Expansion Valve (EEV) control malfunction
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Replace
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Suction and discharge pressures tend to equalize when unit is operating
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Compressor operating in reverse
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Section 6.12
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Compressor cycling / stopped
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Check
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6.8Abnormal Noise or Vibrations
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Compressor
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Compressor start up after an extended shutdown
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Normal
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Brief chattering when manually shut down
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Compressor operating in reverse
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Section 6.12
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Mounting bolts loose or resilient mounts worn
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Tighten / Replace
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Upper mounting loose
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Slugging loose
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Condenser Fan
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Bent, loose or striking venturi
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Check
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Motor bearings worn
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Section 7.3
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Motor shaft bent
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Section 7.3
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Evaporator Fan
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Bent, loose or striking venturi
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Check
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Motor bearings worn
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Section 7.6
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Motor shaft bent
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Section 7.6
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6.9Microprocessor Malfunction
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Will not control
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Software and/or controller configuration incorrect
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Check
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Sensor defective
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Section 7.10
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Wiring defective
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Check
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Refrigerant charge low
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6.10No Evaporator Air Flow or Restricted Air Flow
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Evaporator coil blocked
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Coil has frost build-up
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Section 6.6
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Coil dirty
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Section 7.6
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No or partial evaporator air flow
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Evaporator fan motor internal protector open
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Section 7.6
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Evaporator fan motor(s) defective
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Section 7.6
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Evaporator fan(s) loose or defective
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Section 7.6
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Evaporator fan contactor defective
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Replace
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6.11Electronic Expansion Valve Malfunction
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Low suction pressure
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Software and/or controller configuration incorrect
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Check
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Suction Pressure Transducer (SPT) or Evaporator Pressure Transducer (EPT) failed
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Replace
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Suction Service Valve partially closed
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Open
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Filter drier partially plugged
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Section 7.5
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Refrigerant charge low
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Evaporator air flow not existent or air flow restricted
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Section 7.6
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Evaporator coil excessive frost build-up
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Section 7.6
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Evaporator fan(s) rotating backwards
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Section 7.6
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Electronic Expansion Valve (EEV) control malfunction
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Section 7.7
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Sensor loose or insufficiently clamped
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Replace
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High suction pressure with low superheat
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Valve contains foreign material
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Section 7.7
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Suction Pressure Transducer (SPT) or Evaporator Pressure Transducer (EPT) failed
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Replace
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Electronic Expansion Valve (EEV) control malfunction
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Section 7.7
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Powerhead improperly seated
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Ensure powerhead is locked and in place
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Liquid slugging in compressor
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Suction Pressure Transducer (SPT) or Evaporator Pressure Transducer (EPT) failed
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Replace
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Electronic Expansion Valve (EEV) failed
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Section 7.7
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6.12Compressor Operating in Reverse
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Allowing the scroll compressor to operate in reverse for more than two minutes will result in internal compressor damage. Turn the start-stop switch OFF immediately.
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Electrical
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Compressor incorrectly wired within the VFD.
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Check
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6.13Abnormal Temperatures
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High discharge temperature
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Condenser coil dirty
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Section 7.3
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Condenser fan rotating backwards
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Section 7.3
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Condenser fan inoperative
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Section 7.3
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Refrigerant overcharge or non-condensibles
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Discharge service valve partially closed
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Open
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Electronic Expansion Valve (EEV) control malfunction
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Replace
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Suction Pressure Transducer (SPT) or Evaporator Pressure Transducer (EPT) failed
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Replace
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Discharge temperature sensor drifting high
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Replace
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Economizer Expansion Valve (EEV), Economizer Expansion Valve (ECV) failed or plugged
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Replace
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Sensor loose or insufficiently clamped
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Replace
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6.14Abnormal Currents
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Unit reads abnormal currents
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Current sensor wiring
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Check
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