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

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

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

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.