Vertiv | Liebert PEX4 | User Manual
83
Troubleshooting
Symptom
Potential Causes
Items to be Checked or Handling Process
Low suction
pressure or back
fluid
Lack of refrigerant in
the system
Check for leakages while maintenance and adding the refrigerant.
Dirty air filter
Replace the air filter.
Filter dryer clogging
Replacing the filter dryer.
Improper setting of
Electronic Expansion
Valve superheat
Adjust the Electronic Expansion Valve control parameter as factory
default settings or add the right amount of refrigerant.
Electronic Expansion
Valve device failure
Replacement of Electronic Expansion Valve.
Poor air flow
distribution
Check the supply air, return air flow system.
Condensing pressure is
too low
Check the condenser system.
External static pressure
is large, leading to air
flow attenuation
Check the air flow duct or re-evaluate external static pressure.
Compressor
excessive noise
Back flow of liquid
refrigerant
Check for “if the suction pressure is low” or back flow of liquid.
Poor lubrication
Add refrigerant oil
Compressor transport
fixture not removed
Remove transportation fasteners/fixtures
The compressor
running reversely
Refer to “After starting, suction and discharge pressure unchanged”.
Operation of
the compressor
overheating
Compression ratio is
high
Check the evaporator and condenser fans are operating correctly.
Suction superheat is
high
Adjust the Electronic Expansion Valve settings or add the appropriate
amount of refrigerant.
Remarks: The basis of above symptoms are based on the existing CFC.
