18
5.0 TROUBLESHOOTING
SYMPTOM
POSSIBLE CAUSE(S
CORRECTIVE ACTION
5.1 Indicator lights not illuminated
No power to unit
On/Off Switch off
Switch malfunctioning
Check voltage at terminal board.
Turn on.
Replace switch.
5.2 Moisture Indicator turns yellow
(elevated outlet dew points)
Maximum flow being exceeded
Design conditions being exceeded
Desiccant not adsorbing
a. Useful service life has ended
b. Desiccant is contaminated
(e.g. with oil)
c. Premature exhaustion (saturated with water)
Refer to Table 3A to determine maximum flow.
Refer to Section 3.5 to determine if dryer is being operated within its design
limitations.
Change desiccant.
Take corrective action. Refer to Section 2.1 to determine proper prefiltration
then change desiccant.
Refer to 5.3 for corrective action. Desiccant beds may be reactivated by running
at reduced flow until desired outlet dewpoint is achieved.
5.3 Desiccant being exhausted
prematurely
Insufficient purge rate
a. Improper purge rate
b. Tower not completely depressurized during
purge cycle (Tower pressure gauge should read
lower than 2 psig)
1. Clogged exhaust muffler
2. Purge valve won’t open
3. Check valve stuck open
Insufficient purge time
a. Improper set points
b. Faulty Timer
Refer to Section 3.1.4 to determine correct Purge Pressure Indicator Setting.
Replace muffler inserts.
Check power to valve to determine if valve or timer at fault.
Check pilot air line for obstruction.
Repair valve.
Refer to Section 3.1.1 to determine correct Economizer Switch and Cycle Set-
tings.
Refer to Section 3.2.3 to verify proper time sequence.
5.4 Tower fails to pressurize to line
pressure
Purge repressurization valve won’t close
Excessive downsteam air demand
Check valve for obstruction. This valve is normally closed.
Check pilot solenoid valve and pilot air line for obstruction.
5.5 Tower fails to depressurize to less
than 2 psig
Purge rate valve open too far
Clogged muffler
Check valve stuck open
Purge repressurization valve won’t open
Check Section 3.1.4 for purge rate indicator setting.
Replace muffler.
Repair valve.
Check power to valve to determine if valve or timer is at fault. Check pilot valve,
pilot air line, and purge repressurization valve for obstruction.
5.6 Excessive purge air is discharged
during purge cycle
Inlet valve won’t close
Check valve sticking
Check power to valve to determine if valve or timer is at fault.
Check valve for obstruction. Check pilot valve and pilot air line for obstruction.
Repair Valve
5.7 Excessive desiccant dust
downstream
Faulty timer
Purge rate valve closed
Refer to Section 3.2.3 to verify proper time sequence.
Refer to Section 3.1.4 to determine Correct Purge Pressure setting.
5.8 Switching Failure
Unit did not depressurize in time
(24 sec) or below 10#
Unit did not repressurize in time
(24 sec) or not above 40#
Clogged mufflers, faulty check valve, faulty inlet valve or
purge valve, or faulty pressure switch.
Make sure dryer has air pressure, check purge pressure
setting, faulty purge valve, or faulty pressure switch.
Replace mufflers or defective parts.
Provide proper air pressure. Replace defective parts. Set purge pressure per
section 3.1.4.
