Chapter 7 Troubleshooting 59
Liebert_DM 16kW Air Conditioner 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.
Table 7-1 Fan fault removal
Symptom
Possible causes
Handling method
Fan does not
start
No main power supply
Check the rated voltage at L1, L2 and L3
Circuit breaker tripped or
fuse blown
Check the fuse and circuit breaker of the main fan unit
Overload, or MCB tripped
Reset manually, and check the average current
Contactor does not close
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
Control board faulty
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
Fuse board faulty
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
Air flow lose switch alarm
(action )
Check whether the belt is loose or the fan has faulty
Fan failure
Replace the fan
Table 7-2 Troubleshooting of compressor and cooling system
Symptom
Possible causes
Handling method
Compressor does
not start
Power not on (shutdown)
Check the main power switch, fuse or circuit breaker and
the connecting cable
Power overloaded and MCB tripped
Manual reset and check the average current
Circuit connection loosened
Fasten the connections
Compressor coils shorted
Check the motor and replace it if defects are found
Compressor does
not start, contactor
does not close
No demand for cooling
Check the controller state
High voltage switch acted
Check the high voltage switch
Contactor closed,
but compressor
does not start
Fuse blown or circuit breaker disconnected
Check the fuse, circuit breaker and the contactor, and
measure the circuit voltage
Compressor internal circuit breaker open
Check the compressor coils. If the coils are open, they will
reset automatically after they cooled down
Compressor stops
after running for
5mins (1min ~
5mins settable).
Contactor open
Refrigerant leaked, the LP switch does not
close
Check the suction pressure
High exhaust
pressure
Condenser clogged (air-cooled) or
temperature of input water too high
(water-cooled)
Clean the condenser (air-cooled)
Check the cooling water system
Condenser system does not start
Check the operation procedures
Too much frigerant
Check whether or not the subcooling degree is too high
Water flow regulator improperly set
(water-cooled)
Adjust the water flow regulator
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