Emerson DH, VH, DE, VE manual Dehumidification troubleshooting, Glycol pumps troubleshooting

Troubleshooting

Table 23 Compressor and refrigeration system troubleshooting (continued)

Symptom	Possible Cause	Check or Remedy
	Faulty low pressure switch	Repair or replace.
	Dirt or restriction in tubing to	Check and clean tubing.
Compressor continually	pressure stat
cycles
	Defective liquid line solenoid	Check valve and solenoid operator; replace if necessary.
	valve
	Plugged filter-dryer	Replace filter
	High discharge pressure	Check for loss of condenser water or blocked condenser fan
		or coil.
	Defective overload relay	Replace.
Compressor motor	High suction temperature	Reduce suction temperature by expansion valve adjustment
protectors tripping or		or provide desuperheating.
cycling
	Loose power or control circuit	Check all power and control circuit connections.
	wiring connection
	Defective motor	Check for motor ground or short. Replace compressor, if
		either condition is found.
	Low line voltage	Check line voltage and determine location of voltage drop.
	Seized compressor (remove
	bearing head assembly and	Replace compressor.
Compressor cycles on	attempt to rotate crankshaft)
	Compressor motor defective	Check for motor winding short or ground.
locked rotor
	Single phasing	Check voltage across all 3 legs at contactor. Correct source
		problem.
	Liquid refrigerant condensing in	Check and replace valve plates.
	cylinder
	Check control panel for welded
Motor burnout	contactor contacts or welded	Replace defective components.
	overload contacts

Table 24 Dehumidification troubleshooting

Symptom	Possible Cause	Check or Remedy
	Control not calling for	Check monitor status.
	dehumidification
No dehumidification	Compressor contactor not pulling in	See Compressor Section.
	Compressor won't run; fuse blown	See Compressor Section. Check fuses or CBs and
	or CB tripped	contacts. Check line voltage

Table 25 Glycol pumps troubleshooting

Symptom	Possible Cause	Check or Remedy
Suddenly stops	Clogged strainer or impeller	Clean out debris.
pumping
Suddenly slow pumping	Clogged impeller, diffuser, or line	Clean out debris and use strainer.
Excessive leakage
around the pump shaft	Worn seal or packing	Replace seal or packing.
while operating
	Worn impeller or seal	Replace with new impeller or seal.
Performance poor	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
	Worn motor bearings	Replace pump
Noisy operation	Low discharge head	Throttle discharge-improve suction conditions.
	Debris lodged in impeller	Remove cover and clean out.
	Cavitating pumps	Adjust system pressures.

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