Chapter 6 System Maintenance 35
New Liebert_DM Series Air Conditioner User Manual
Chapter 6 System Maintenance
This chapter expounds the system maintenance of the Liebert_DM AC, including electric inspection, indoor unit
maintenance, outdoor unit maintenance and maintenance inspection checklist.
Note
1. Switch off the circuit breaker and cut off the unit power before maintenance unless the power is necessary for the
commissioning item.
2. Even if the indoor unit power is disconnected, the indoor unit fan, heater, outdoor unit fan and humidifier may still carry
hazardous voltage. So switch off the circuit breaker to disconnect the power supply of the system before maintenance.
6.1 Electric Inspection
Visually inspect the control board, power detection board, filter board, display board and THS board on a semi-annual
basis for any loose electric connection and circuit corrosion.
The micro-processing controller has five circuit boards which jointly complete the system fault detection, input and
output.
Inspect the boards one by one according to the procedures below:
1. Do unit electric insulation test to find failed contacts and deal with them.
2. Statically check and test if the contactor is flexible without blocking.
3. Clean the electric and control components with a brush or compressed dry air.
4. Check if the contactor contacts have arc or burned phenomenon when closing.
5. Tighten all electric contacts.
6. Check if the temperature of all MCBs and contactor contacts become higher.
Note
All circuit boards are not hot-pluggable. Big instant current will be produced when the board is plugged or unplugged with
powering on and it may lead to unrepairable damage to the circuit. The control board can only be maintained after the
micro-processing controller is powered off.
6.2 Indoor Unit Maintenance
6.2.1 Filter
The filter is a consumable. Its replacement interval is directly related to the seal and cleanness status of the
equipment room. In order to maintain efficient operation, the filter should be checked monthly and be replaced or
washed as required.
The filters of the indoor unit are installed on the front door and side panel.
Filter on the front door
Unscrew the fixing screws on the filter stator, and remove the filter stator to take out the filter on the front door, as
shown in Figure 6-1.
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