Vertiv | Liebert PEX4 | User Manual
80
Troubleshooting
5.1.2. Heating System Troubleshooting
Refer
for troubleshooting the heating system.
Table 5-2 Diagnosis and Treatment of Heating System
Symptom
Potential Causes
Items to be Checked or Handling Process
Heating system
does not
operate and the
contactor does
not close
No heating demand
Check the PACC controller’s status and confirm whether there is heating
demand.
Heating auxiliary
relay fault
Check if the light next to the heating auxiliary relay is on and whether the
line is correct.
Heating system
safety device failure
•
Use a multimeter to check J21-1 ( for single electrical heating), J21-2
(for two electrical heating), and if the voltage across the terminals G is
about 24 V, then move further to safety means across the resistor and
if the resistance is large, it indicates that the security device must be
disconnected.
•
Check if the manual reset switch is turned off. in case of the reset switch
is automatic, check for damage of electrical heater.
Use an ohmmeter to check if the electrical heater is damaged by
checking the resistance of its resistor.
Contactor
closed, no
heating effect
Main power failure of
heater
•
Check if the air switch heating system is closed or not.
•
If the contactor is closed, check heating engaged state of contactors L1,
L2 and L3 supply voltages is normal.
Heater burnout
Cut off the power supply and use an ohmmeter to check if the electrical
heater is damaged by checking the resistance.
5.1.3. Compressor and AC System Troubleshooting
Table 5-3 Diagnosis and Treatment of Compressor and AC system
Symptom
Potential Causes
Items to be Checked or Handling Process
Compressor can
not start
Power not connected
(off)
Check the main power switch, fuse or circuit breaker and connecting
wires.
Power overload and
MCB tripped
Manual reset, check the average current value.
Loose circuit
connections
Check if circuit connectors are firmly connected.
Short circuit due to
motor winding burnout
Check the static resistance imbalance of motor windings, if found
defective, replace immediately.
Contactor did
not close and
compressor is
not running
No CFC (call for
cooling) output
Check the PACC controller status.
High pressure switch
actuates
•
Check if the wiring of switch is connected to controller.
•
Check if there is high pressure alarm on high pressure switch
status.
