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"Oil-Less" Scroll Laboratory Air
Appendix A: Desiccant Dryer
A.3 Troubleshooting
Problem
Dryer not cycling
Dew point degradation
4107 9006 25.11
Possible Causes
Main power disconnected
Power failure
Main fuse blown
Fuse blown in control circuit
Dryer circuit board failure
Dryer operation in Off position
Loose or faulty connection
Switching valve failure
Incorrect purge air fl ow
Excessive system fl ow rate
Inlet air temperature is above
the dryer's design inlet working
temperature
Liquids entering the dryer inlet
Purge muffl er restricted
A-4
Solution
Turn on main power
Restore power
Replace fuse
Replace fuse
Check and replace if defective
Select Automatic or Manual mode
Check & tighten all wire connections
Replace switching valve
Check purge orifi ce for blockage.
Clean and replace as required
Reduce inlet fl ow rate and/or increase
operating pressure
Check the compressor aftercooler and
cooling system. Adjust as necessary
to bring the dryer inlet temperature
to less than the maximum design
working temperature of 43°C (110°F)
Isolate and depressurize the pre-fi lter
assembly. Inspect pre-fi lter cartridges
and end seals for loosening and/
or damage. Tighten or replace as
necessary.
Inspect the pre-fi lter automatic drain
valve. Ensure that it is not clogged
and is draining properly. Repair or
replace as necessary, if a problem is
noted.
Replace muffl er.
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Troubleshooting
