Liebert CR012 Precision Air Conditioning User Manual
Chapter 4 Maintenance & Troubleshooting 55
2. Ensure no sediments, debris, foreign matter, or leakage occurs in the water tray.
4.10 Troubleshooting
Troubleshooting is to be performed by the trained and qualified service personnel. However, the checklists have
been provided just for reference purposes.
⚫ Certain circuits carry lethal voltages. Only professional technicians are allowed to maintain the machine. Extreme care
and caution is required while troubleshooting online.
⚫ If jumpers are used for troubleshooting, remember to remove the jumpers after the troubleshooting failing which the
connected jumpers may bypass certain control functions and increase the risk to the equipment.
Table 4-3 Troubleshooting the fan
Power Supply
Disconnected
Check whether the fan MCB is closed; If the MCB is closed, check if the power
voltage of each phase is normal
Check J15 on the micro-processing control board, to ascertain whether the control
board is faulty or functions correctly
Check the alarm lamp on the fan power module to ascertain whether it is faulty or
functions correctly
Check L1, L2, and L3 of the fan against power failure, phase loss, and low voltage
Check whether the analog output is within the specific range of 0 ~ 10Vdc as per
the requirement
Check whether the motor is clogged (due to large current)
Check whether the motor is too hot
⚫ If the previous three problems (i.e. Motor Clogging, Hot Motor, or Hall failure) occurs, the motor can restore
normal operation after the faults are cleared.
⚫ If the motor is too hot, cut off the fan power; after the motor cools down, power on it again for recovery.
⚫ In the event of a hall failure, factory service is required to fix the issue.
Troubleshooting of the Heating system
Table 4-4 Troubleshooting the Heating system
Items to be checked or handling method
Heating system does
not start, the
contactor does not
close
Check the state of the micro-processing controller, and confirm if there is a
requirement for the heating command
Safety device of
the heating
system is open
Use a multi-meter to measure the resistance on both ends of the temperature
controller; if the resistance is very large, it indicates that the safety device may be
open. Next, check whether the fuse is open and the temperature controller is
damaged. Measure the resistance of the heater with an ohmmeter to judge if the
heater is damaged
The Contactor
closes, but heating is
ineffective
Check if the heater's MCB is turned ON; Check whether the L1, L2, and L3 voltages
are normal when the contactor is energized
Turn off the power; then physically check the condition of the heater
Troubleshooting of compressor and cooling system
Table 4-5 Troubleshooting the Cooling system
Items to be checked or handling method
Does not power on (Shutdown)
Check the main power against under-voltage, over-
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