Chapter 8 Troubleshooting 73
Liebert. PEX+Series Precision Air Conditioner User Manual
Heating system cannot start, the
contactor cannot close
Heating auxiliary relay failure
Check the heating auxiliary relay and its cable
Safety device of the heating
system is open
In the case of two-stage heating, check terminals P34-1
and P34-2. If the heating system then starts to work, it
means that the safety device is open. Remove the jumper
and the electric heater, and check that the manual reset
switch is open, meanwhile, check that the automatic reset
switch is damaged. To judge whether the electric heater
is damaged, you can use an Ohm meter to check the
resistance status of the electric heater
Air flow lose switch failure
Check that the air flow lose switch connection is correct.
Examine whether there is24Vac voltage between P36-7
and E1 after startup, if there is not, you should check
whether the air flow lose switch is damaged
Contactor closes, but heating is
ineffective
Electric heater main power
failure
Check that the electric heater MCB is closed;
In humidifier contactor closed state, check that L1, L2 and
L3 voltages are normal
Electric heater burned
Cut off the power supply and measure the resistance of
the heater with an Ohm meter
