A-4
“Oil-Less” Scroll Laboratory Air
4107 9006 25.11
Appendix A: Desiccant Dryer
Problem
Possible Causes
Solution
Dryer not cycling
Main power disconnected
Turn on main power
Power failure
Restore power
Main fuse blown
Replace fuse
Fuse blown in control circuit
Replace fuse
Dryer circuit board failure
Check and replace if defective
Dryer operation in Off position
Select Automatic or Manual mode
Loose or faulty connection
Check & tighten all wire connections
Switching valve failure
Replace switching valve
Dew point degradation
Incorrect purge air fl ow
Check purge orifi ce for blockage.
Clean and replace as required
Excessive system fl ow rate
Reduce inlet fl ow rate and/or increase
operating pressure
Inlet air temperature is above
the dryer’s design inlet working
temperature
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)
Liquids entering the dryer inlet
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.
Purge muffl
er restricted
Replace muffl
er.
A.3 Troubleshooting