Vertiv
™
| Liebert® XDC | User Manual
56
Symptom
Possible Cause
Items to be Checked or Handling Method
Low exhaust
pressure
The outdoor fan speed controller is
faulty, and the output voltage is always
full load voltage, and does not change
with the change of condensing pressure
(air cooling)
If defects are found, replace the speed controller
immediately
After starting,
there is no
change in
suction and
exhaust
pressure
Compressor runs reversely or internal
air blistering
If the compressor runs reversely, replace any two L
wires of the compressor (inverter output terminal); if
internal air leakage occurs and cannot be recovered,
the compressor needs to be replaced
Low suction
pressure or
liquid backflow
Insufficient refrigerant in the system
Check for leaks. If yes, repair and add refrigerant
Filter net of the terminal is too dirty
Replace the filter net
Clogged dry filter
Replace the dry filter
Improper setting of the superheat of
the electronic expansion valve of the
terminal
Operate strictly in accordance with the design
superheat of the unit
Electronic expansion valve device of the
terminal failure
Replace electronic expansion valve
Poor air distribution
Check the air supply and air return system
Condensing pressure is too low
Check the condenser
Compressor
noise is too loud
Liquid backflow
See “Low suction pressure or liquid backflow” handling
method
Poor lubrication
Add lubricant
The compressor transportation fixture is
not removed
Remove the transportation fixture
Compressor
overheated
Compression ratio is too high
• Check the settings of the high pressure and low
pressure switches, check whether the condenser is
dirty or blocked;
• Check whether the evaporator and condenser fan
of the terminal are operating normally
Suction superheat is too high
Adjust the setting of the electronic expansion valve of
the terminal or add a proper amount of refrigerant
