Chapter 7 Troubleshooting - Liebert DM User Manual

Chapter 7 Troubleshooting

This chapter introduces the troubleshooting. You can read this part by referring to the part concerning the alarms.

Caution
1. Certain circuits carry lethal voltages. Only professional technicians are allowed to maintain the machine.
2. Extra care should be taken when troubleshooting online.

Note
If jumpers are used for troubleshooting, remember to remove the jumpers after the troubleshooting, or the connected jumpers
may bypass certain control function and become a potential risk to the equipment.
Symptom Possible causes
No main power supply
Circuit breaker tripped or
fuse blown
Overload, or MCB tripped
Contactor does not close
Fan does not
Control board faulty
start
Fuse board faulty
Air flow lose switch alarm
(action )
Fan failure
Symptom
Power not on (shutdown)
Compressor does
Power overloaded and MCB tripped
not start
Circuit connection loosened
Compressor coils shorted
Compressor does No demand for cooling
not start, contactor
High voltage switch acted
does not close
Fuse blown or circuit breaker disconnected
Contactor closed,
but compressor
does not start
Compressor internal circuit breaker open
Compressor stops
after running for
Refrigerant leaked, the LP switch does not
5mins (1min ~
close
5mins settable).
Contactor open
Condenser clogged (air-cooled) or
temperature of input water too high
(water-cooled)
High exhaust
Condenser system does not start
pressure
Too much frigerant
Water flow regulator improperly set
(water-cooled)
Table 7-1 Fan fault removal
Check the rated voltage at L1, L2 and L3
Check the fuse and circuit breaker of the main fan unit
Reset manually, and check the average current
Check the voltage between P36-3 and E1. If there is a 24Vac, while the
contactor does not close, the contactor is faulty. Replace the contactor
Check the voltage between P36-3 and E1. If there is no 24Vac, the control board
is faulty. Check the state of the green indicator beside Q5 on the control panel
Check the voltage between P36-3 and E1. If there is no 24Vac, and the green
indicator beside Q5 is off, check the indicator DS4 beside fuse F4 on the fuse
board, or take down the F4 fuse tube to see whether or not it has blown
Check whether the belt is loose or the fan has faulty
Replace the fan
Table 7-2 Troubleshooting of compressor and cooling system
Possible causes
Liebert_DM 16kW Air Conditioner User Manual
Chapter 7 Troubleshooting
Handling method
Handling method
Check the main power switch, fuse or circuit breaker and
the connecting cable
Manual reset and check the average current
Fasten the connections
Check the motor and replace it if defects are found
Check the controller state
Check the high voltage switch
Check the fuse, circuit breaker and the contactor, and
measure the circuit voltage
Check the compressor coils. If the coils are open, they will
reset automatically after they cooled down
Check the suction pressure
Clean the condenser (air-cooled)
Check the cooling water system
Check the operation procedures
Check whether or not the subcooling degree is too high
Adjust the water flow regulator
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