AEC WD 350 through WD3000 Dehumidifying Dryers - Manual (Page 74)

Problem Possible cause Corrective action
Airflow valve sticking or
failing to shift.
Check for proper operation of
valve actuators. Repair or
replace if necessary.
Remove blower side plate,
clean baffles, replace.
Loss or reduction in drying
capacity. (cont’d.)
Blower fins filled with dust or
contaminants.
Replace filter elements.
Insufficient power to PLC
(Power LED is off).
Check power supply and
power wiring to PLC.
PLC Regeneration Bed LED
indicators both off.
Faulty PLC (PLC Power light
is on, Run light is off, and/or
Error light is on). Replace PLC.
Regenerating bed cooldown. None.
Blower Input indicator is off.
Verify that blower contactor is
on. Check input wiring to
PLC.
Process air in high-
temperature condition.
None.
Insufficient power to PLC
(Power light is off).
Check power supply and
power wiring to PLC.
PLC Regeneration Heater
Left/Right output indicators
both off.
Faulty PLC (PLC Power light
is on, Run light is off, and/or
Error light is on). Replace PLC.
Process temperature set too
high due to operator error.
Check resin manufacturer’s
data sheet for proper drying
temperature. Make sure plant
personnel are aware of the
correct process temperature
set point.
High temperature alarm not
set properly.
Reset high temperature
alarm. See Section 6-5 on
Page 43 for more
information.
Process set point is out of
acceptable range. Restore temperature
controller to factory pre-sets.
Function set for degrees
Celsius (ºC), set point at
degrees Fahrenheit (ºF).
Verify correct Celsius or
Fahrenheit settings.
Material in drying hopper
cakes, or meltdown occurs.
Process thermocouple not in
airflow.
Verify that the thermocouple
is properly installed in the
inlet tube.
Burned out regeneration
heater.
Repair or replace.
Contaminated or worn out
desiccant.
Replace.
Leaking process air hoses. Repair or replace.
Dryer operates beyond its
capacity. Check dryer and drying
hopper sizing.
Poor dew point performance.
Bad dew point sensor. Replace.
WDMR and WDFR Series Dehumidifying Dryers Page 73