Liebert himod - Table 22 Dehumidification Troubleshooting; Table 23 Glycol Pump Troubleshooting

60 Troubleshooting
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-drier Replace filter.
Compressor motor protectors
tripping or cycling
High discharge pressure
Check for loss of condenser fluid or blocked
condenser fan or coil.
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.
Compressor motor defective Check for motor winding short or ground.
Single phasing
Check voltage across all 3 legs at contactor.
Correct source problem.
Motor burnout
Check control panel for welded
contactor contacts or welded
overload contacts
Replace defective components.
Table 22 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 23 Glycol pump 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 21 Compressor and refrigeration system troubleshooting (continued)
Symptom Possible Cause Check or Remedy