Emerson Liebert PEX Series User Manual page 102

Symptom
Heating system cannot start, the
contactor cannot close
Contactor closes, but heating is
ineffective
Affiliated table 1: Monthly maintenance table
Inspection date: ___________________
Unit model: ___________________
Filters:
___ 1. Check for clogging or damage
___ 2. Check the filter clog switch
___ 3. Clean the filter
Fan
___ 1. Fan blades are not distorted
___ 2. Whether there is bearing wear
___ 3. Belt tightness and its state
Compressor
___ 1. Check for leakage
___ 2. Listen to the operation sound, observe the
operation vibration
Air-cooled condenser (if used)
___ 1. Check the fins clean
___ 2. The fan base should be firm
___ 3. The fan vibration absorber is not deteriorated
or damaged
___ 4. The SPD board should be effective (in the
storming seasons, the SPD board should be check
once a week)
Signature: _________________________________________________________
Note: copy this table for filing.
Table 8-4 Troubleshooting of heating system
Potential causes
No heating demand
Heating auxiliary relay failure
Safety device of the heating
system is open
Air flow lose switch failure
Electric heater main power
failure
Electric heater burned
Liebert.PEX2 Series Air Conditioner User Manual
Chapter 8 Troubleshooting
Items to be examined or handled
Check the state of the iCOM controller, and verify
whether there is a humidifying demand
Check the heating auxiliary relay and its cable
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
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
Check that the electric heater MCB is closed;
In humidifier contactor closed state, check that L1, L2 and
L3 voltages are normal
Cut off the power supply and measure the resistance of
the heater with an Ohm meter
Prepared by: ___________________
Unit SN: ___________________
___ 5. The refrigerant pipes are properly supported
Refrigeration cycling system
___ 1. Check the suction pressure
___ 2. Check the discharge pressure
___ 3. Check the refrigerant pipes
___ 4. Check the moisture content (through the
sight glass)
___ 5. Check the hot gas bypass valve
___ 6. Check the thermal expansion valve
___ 7. Check the dual cooling/free cool unit water
inlet temperature
Heating system
___ 1. Check the re-heater operation
___ 2. Check the erosion situation of the
components
Infrared humidifier
___ 1. Check clogging of the drain pipes
___ 2. Check the lamps of the humidifier
___ 3. Check the mineral sediments on the water
pan
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