Chapter 7 Troubleshooting; Fan Troubleshooting; Infrared Humidifier Troubleshooting; Compressor And Cooling System Troubleshooting - Liebert PEX+ Series User Manual

This chapter introduces the troubleshooting of Liebert.PEX+ AC, mainly including the troubleshooting and fault
handling of fan, infrared humidifier, compressor and cooling system, and heating system, and the simple
troubleshooting and faults handling that can be performed by users. Please contact Emerson for complex
troubleshooting and fault handling.
Certain circuits carry lethal voltages. Only professional technicians are allowed to maintain the unit. Extra care should be
taken when troubleshooting a live unit.
If jumpers are used for troubleshooting, remember to remove the jumpers after the troubleshooting. The connected
jumpers may bypass certain control function and damage the equipment.

7.1 Fan Troubleshooting

The fan troubleshooting is listed in Table 7-1.
Symptom
ECfan cannot be
started
Air loss alarm is
displayed

7.2 Infrared Humidifier Troubleshooting

See Table 7-2 for infrared humidifier troubleshooting.
Symptom
Humidification
ineffective

7.3 Compressor and Cooling System Troubleshooting

See Table 7-3 for troubleshooting compressor and cooling system.

Chapter 7 Troubleshooting

Table 7-1 Fan fault removal
Potential causes
MCB disconnection
Control board failure
the filter is clogged
Table 7-2 Troubleshooting of infrared humidifier
Potential causes
Check that the water supply is normal
Check that the water supply solenoid valve is working
No water in the water
pan
Check the state of the high water-level switch and water level regulator
Check that the water supply pipe is not clogged
Check if the contactor voltage is normal
The humidification
Check if the safety devices of the infrared humidifier are opened, such as water
contactor does not
pan over-temperature protection switch and over-temperature protection switch at
close
top.
Humidifier main power Check that the humidifier MCB is closed;
failure In humidifier contactor closed state, check that L1, L2 and L3 voltages are normal
Infrared humidifier
Replace the lamp
lamp burned
Liebert. PEX+Series Precision Air Conditioner
Items to be examined or handled
Examine the MCB of main fan , check if the fans L1, L2 and L3 are power-off, or
have phase failure or undervoltage
1} Check if the green LED beside the relay K1 on the control panel is on or not
to judge is the board fails
2)Check if J64 has 0~10Vdc analog output, if no, check the control board.
Check if the filter is clogged that causes low air flow, if so, replace the filter
Items to be examined or handled
Chapter 7 Troubleshooting
User Manual
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