15
5.3 Alarm L3 - Failure to depressurize, left tower, regeneration cycle
1. Faulty left tower pressure switch (PS1)
• See Section 5.1.3.
2. Left depressurization muffler (M1)
• Examine inner core and clean or replace as necessary.
clogged
3. Left depressurization valve (V5)
• Check valve operation. Repair or replace as necessary.
failed to open
4. Left purge exhaust piping obstructed
• Ensure piping is free of obstructions.
5. Left purge valve (V3) failed to open
• Loss of pilot air - see Section 5.1.4.
• Left purge pilot valve (V13) failure - check valve operation. Repair or
replace as necessary.
• Left purge valve (V3) - examine valve and actuator for damage.
Repair or replace as necessary.
6. Repressurization valve (V15)
• Loss of pilot air - see Section 5.1.4.
failed to close
• Pilot valve (V16) failure - check valve operation. Repair or replace as
necessary.
• Repressurization valve (V15) - examine valve and actuator for dam-
age. Repair or replace as necessary.
5.4 Alarm L4 - Low or no blower pressure, left tower, regeneration cycle
1. Blower intake filter (F1) clogged
• Examine intake filter element and clean or replace.
2. Improper setting on blower pressure
• Check pressure switch operation. Readjust switch setting or replace
switch (PS3)
switch if defective.
3. Loss of pressure to blower pressure
• Check lines for leaks, cracks, loose fittings, etc. Repair as necessary.
switch (PS3)
4. Other alarms preventing motor starter
• Check for Alarms L3 (see Section 5.3) and L5 (see Section 5.5) and
from being energized
correct as necessary.
5. No power to motor
• Check wiring and control components in motor circuit. Repair as
necessary.
6. Low Pilot Air Pressure (PPS)
• Check switch operation, check system pressure.
5.5 Alarm L5 - High heater element temperature, left tower, regeneration cycle
1. False alarm
• Heater hi-limit thermocouple - check thermocouple circuit for
continuity.Repair or replace as necessary.
• Heater hi-limit controller (TC2) or (TC4) malfunction - check controller
operation.Repair or replace as necessary.
2. Improper (high) setting on heater
• Adjust to factory setting.
outlet temperature controller (TC1)
3. Restricted or blocked purge air flow
• Dirty intake filter (F1) on blower - examine filter element and clean or
replace.
• Left purge valve (V3) failed to open - see Section 5.3.5.
• Left purge exhaust piping obstructed - ensure piping is free of
obstructions.
• Left purge check valve (V9) failed to open - examine valve internals.
Repair or replace as necessary.
4. High temperature at blower discharge
• Right purge valve (V10) is leaking - see Section 5.15.6
• Resricted or blocked purge air flow - see Section 5.5.3
5.6 Alarm L6 - Incomplete heating, left tower, regeneration cycle
1. Desiccant bed overloaded on
• See Section 5.2.1.
previous drying cycle
2. Heater outlet temperature too low
• Incorrect (low) setting on heater temperature controller (TC1) - adjust
to factory setting.
• Electrical short in heater element(s) - check resistance of each phase
in the heater circuit.
3. Incorrect (high) setting on left purge
• Check switch operation, using temperature gauge (TI1) for compari-
temperature switch (TS1)
son. Readjust switch setting or replace switch if defective.
4. No power to heater
• Check wiring and control components in heater circuit. Repair as
necessary.
• Heater outlet thermocouple - check thermocouple circuit for conti-
nuity. Repair or replace as necessary.
• Low or no blower pressure - check for Alarm L4 (see Section 5.4).
• Heater outlet temperature controller (TC1) malfunction - check
controller operation. Repair or replace controller as necessary.
5. Restricted or blocked purge air flow
• See Section 5.5.3.
6. Low pilot air pressure (PPS)
• Check switch operation, check system pressure.
POSSIBLE CAUSES
CORRECTIVE ACTION
