Table 14 Compressor And Refrigeration System Troubleshooting - Emerson Liebert Challenger 3000 Operation & Maintenance Manual

Table 14 Compressor and refrigeration system troubleshooting
Symptom
Compressor will not start
Compressor will not operate,
contactor not pulling in
Compressor will not operate,
contact not pulling in
Compressor contactor pulled in but
compressor will not operate
Compressor runs for three minutes
then stops; contactor drops out.
High discharge pressure
Low discharge pressure
Low suction pressure
Possible Cause
Power Off
Current overload open
Loose electrical connections
Compressor motor burned out
No call for cooling
Solenoid valve not energizing
Low pressure switch not making contact
High pressure switch open
Blown fuse or tripped CB
Low pressure switch not closing
Liquid line solenoid valve not opening
Dirty condenser or drycooler fins
Condenser equipment not operating
High refrigerant charge
Hot gas bypass valve adjusted
improperly
Water regulating valve adjusted
improperly
Excessive fluid flow through condenser
Suction service valve partially closed
Faulty head pressure control valve or
condenser fan speed control
Compressor rotation in reverse direction
Insufficient refrigerant in system
Dirty air filters
Plugged filter-drier
Improper superheat adjustment
Defective expansion valve sensing
element
Poor air distribution
Low condensing pressure
Slipping belts
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Troubleshooting
Check or Remedy
Check main switch, fuses or CBs and
wiring
Re-set units with overload option
manually. Allow compressor to cool for
internal overloads to reset.
Tighten connections
Check and replace compressor if
defective.
Check monitor status.
Hold screwdriver over solenoid and check
for magnetic field. This indicates solenoid
is energized.
Check gas pressure - manually energize
low pressure switch.
Reset switch. Refer to other refrigeration
troubleshooting suggestions.
Check for line voltage after fuses or CBs,
and after contactors.
Check for low gas pressure. Compressor
is running on Positive Start Kit (air cooled
systems only)
Check magnetic field to see if energized.
Clean coil.
Check operation.
Check refrigerant charge.
Adjust properly.
Adjust properly.
Adjust fluid regulating valve
Open the valve.
Replace if defective.
Check for proper power phase wiring to
unit and to compressor motor.
Check for leaks, repair, and add
refrigerant for air cooled. Evacuate and
recharge for water/glycol unit.
Change filters.
Replace filter.
Reset expansion valve for 10-15
(6-8°C)
Replace element
Check duct work for closed dampers.
Check for under-floor restrictions at or
near the unit.
Check head pressure control device.
Inspect and adjust
°
F