10. Troubleshooting
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10. Troubleshooting
10. Troubleshooting
SYMPTOM
POSSIBLE CAUSE(S)
CORRECTIVE ACTION
No power to unit.
Check voltage at terminal board.
Off/On switch turned off.
Turn on.
Blown fuse.
Replace fuse
10.1 Indicator lights not
illuminated
Off/on switch or board malfunction.
Replace board.
Design conditions exceeded.
Refer to Sections 4 & 8 to determine if dryer is being operated outside of design
limitations.
Spent desiccant (useful service life has ended).
Replace desiccant.
Contaminated desiccant (e.g. with oil)
Take corrective action. Refer to Section 4.1 to determine proper prefiltration before
changing desiccant.
10.2 Moisture Indicator
turns yellow (elevated
outlet dew point)
Saturated desiccant (saturated with water)
Refer to 10.3 for corrective action. Operation at reduced flow may reactivate
desiccant beds until desired outlet dew point is achieved.
Insufficient purge flow - Purge pressure too low
Refer to Section 8 to determine correct Purge Pressure Indicator setting .
Incomplete tower depressurization (tower pressure greater
than 2 psig) - Clogged mufflers
Replace muffler inserts
Incomplete tower depressurization -
Purge/repressurization valve fails to open
Verify voltage to pilot solenoid valve. Check pilot air pressure (60-120 psig req'd.)
Verify proper actuator operation.
Insufficient purge time -
Incorrect controller settings
Refer to Section 6 or 7 to determine correct controller cycle settings.
10.3 Premature saturation
of desiccant
Insufficient purge time -
Faulty controller
Refer to Section 6 or 7 to verify proper time sequence. Replace controller board as
req'd.
Purge/repressurization valve fails to close (air loss from
mufflers during tower repressurization portion of cycle)
Verify removal of voltage to pilot solenoid valve. Verify proper actuator operation. This
is a spring-assisted, normally closed valve. Check valve for obstruction or seat
damage.
10.4 Tower fails to re-
pressurize to line pressure
Insufficient purge flow -
Purge pressure too low
Refer to Section 8 to determine correct Purge Pressure Indicator setting . Purge
Pressure Adjustment Valve should never be completely closed.
Excessive purge flow -
Purge pressure too high
Refer to Section 8 to determine correct Purge Pressure Indicator setting .
Inlet switching valve fails to close.
Verify voltage to pilot solenoid valve. Check pilot air pressure (60-120 psig req'd.)
Verify proper actuator operation. Check valve for obstruction or seat damage.
10.5 Excessive purge is
discharged during purge
cycle
(Models 40 through 450) Shuttle Valve; or (Models 590
through 5400) same tower Outlet Check or opposite tower
Purge Check Valves fail to close.
Repair or replace valve(s) as needed.
Fluidization of desiccant bed - design conditions for maximum
rated flow exceeded
Refer to Section 4 or 8 to determine if dryer is being operated outside of design
limitations.
10.6 Excessive desiccant
dust downstream
Fluidization of desiccant bed –
Rapid repressurization of offstream tower due to:
Faulty timer
Insufficient purge flow - purge pressure too low
Refer to Section 6 or 7 to verify proper time sequence.
Refer to Section 8 to determine correct Purge Pressure Indicator setting .
Faulty pressure switches or control board
Replace components
Offstream tower did not de-pressurize in time and/or below 10
psig
Check mufflers, check or shuttle valve(s), inlet switching and
purge/repressurization valves, purge pressure adjustment,
and controller settings.
10.7 Switching Failure
Alarm
Offstream tower did not re-pressurize in time and/or above 10
psig
Check air supply to dryer, purge/repressurization valve, purge
pressure adjustment, and controller settings.
