Emerson Liebert Deluxe System/3 DH - Manual (Page 75)

Troubleshooting
67
Compressor continually
cycles
Faulty low pressure switch Repair or replace.
Dirt or restriction in tubing to
pressure stat
Check and clean tubing.
Defective liquid line solenoid
valve
Check valve and solenoid operator; replace if necessary.
Plugged filter-dryer Replace filter
Compressor motor
protectors tripping or
cycling
High discharge pressure
Check for loss of condenser water or blocked condenser fan
or coil.
Defective overload relay Replace.
High suction temperature
Reduce suction temperature by expansion valve adjustment
or provide desuperheating.
Loose power or control circuit
wiring connection
Check all power and control circuit connections.
Defective motor
Check for motor ground or short. Replace compressor, if
either condition is found.
Compressor cycles on
locked rotor
Low line voltage Check line voltage and determine location of voltage drop.
Seized compressor (remove
bearing head assembly and
attempt to rotate crankshaft)
Replace compressor.
Compressor motor defective Check for motor winding short or ground.
Single phasing
Check voltage across all 3 legs at contactor. Correct source
problem.
Liquid refrigerant condensing in
cylinder
Check and replace valve plates.
Motor burnout
Check control panel for welded
contactor contacts or welded
overload contacts
Replace defective components.
Table 24 Dehumidification troubleshooting
Symptom Possible Cause Check or Remedy
No dehumidification
Control not calling for
dehumidification
Check monitor status.
Compressor contactor not pulling in See Compressor Section.
Compressor won't run; fuse blown
or CB tripped
See Compressor Section. Check fuses or CBs and
contacts. Check line voltage
Table 25 Glycol pumps troubleshooting
Symptom Possible Cause Check or Remedy
Suddenly stops
pumping
Clogged strainer or impeller Clean out debris.
Suddenly slow pumping Clogged impeller, diffuser, or line Clean out debris and use strainer.
Excessive leakage
around the pump shaft
while operating
Worn seal or packing Replace seal or packing.
Performance poor
Worn impeller or seal Replace with new impeller or seal.
Suction lift too high Relocate pump closer to supply.
Motor not up to speed; low voltage
Larger lead wires may be required Check for proper
line voltage (±10%).
Worn bearings Replace pump
Noisy operation
Worn motor bearings Replace pump
Low discharge head Throttle discharge-improve suction conditions.
Debris lodged in impeller Remove cover and clean out.
Cavitating pumps Adjust system pressures.
Table 23 Compressor and refrigeration system troubleshooting (continued)
Symptom Possible Cause Check or Remedy