12.9.2 If there is a Humidity Alarm, the Display will
rst indicate the Time and Date of the Alarm, and show
a Minor Alarm (Blinking Green/Red LED). If after 5
minutes of continuous operation in alarm, the Dryer
status condition changes to a Major Alarm (solid Red
LED) and shuts down. The bypass solenoid valve is
de-energized and all air is bypassed out through the
System Controller mufer. The Alarm Segregation
and CO Alarms will be transmitted upon Humidity.
12.9.3 If in Humidity, restart the Dryer by resetting
the Alarm or by turning the Power switch OFF then
ON. Then remove the air hose from the sensor by
depressing the ring collar on the white tting and
pulling off the hose. NOTE: Do not remove the
tting from the Sensor Board as the Humidity sensor
could be damaged. Place the tip of a nger over the
end of the hose and verify a slight movement of air.
12.9.4 If there is no air movement, the vent orice
located inside the tube (the one that has a tie wrap
around it) and located close to the Humidity Bypass
Solenoid Valve (9) is most likely plugged. It will
need to be removed and replaced.
12.9.5 If the alarm persists after the previous steps
have been performed, and the air is above 5%RH,
there are ve conditions which can cause a valid
humidity alarm: low System Pressure, interrupted
purge cycling, excessive compressor air ow
capacity, restricted desiccant tower lters, or dirty/
clogged purge adjusters.
12.9.6 Low System Pressure can cause a Humidity
Alarm, but may not be obvious if the System Pressure
is inaccurate. Test the accuracy of the System
Pressure by connecting a test gauge to the test valve
(24) located at the top of the Sight Tube assembly.
Readjust the System Pressure if it is inaccurate.
Verify that the System Pressure is correc tly adjusted.
12.9.7 Interrupted Dry Pak (38) drying cycle can
cause a Humidity Alarm. Test for correct dryer cycling
by observing the System Pressure for uctuation
while listening for the purge sound each thirty
seconds of operation. If cycling is interrupted, turn
off the power switch (6), disconnect the dehydrator
18
from the electrical service and check the Purge Valve
coils (7) by measuring the coil resistance while
disconnected from the dehydrator elect rical harness.
Coil resistance should be 211 ohms +/- 15% (use an
accurate digital meter). Replace the coil, if it’s open
or shorted.
12.9.7.1 If the coils are OK, but cycling is interrupted,
reconnect the coils, connect electric service and
restart the dehydrator. Check each coil for magnetic
attraction to a very small steel screw driver, when it
is held at the center of the clip which holds the coil
in place. The light magnetic pull can be sensed for
27 seconds at one coil and three seconds later will be
sensed on the coil of the opposite purge valve coil for
27 seconds. If the magnetic attraction is present as
described, but cycling is interrupted, replace the Purge
Valve kits (7). If neither coil displays a magnetic pull
during a full minute of operation, check the condition
of the circuit breaker which protects the timer circuit.
12.9.7.2 If the magnetic attraction is constant on one
coil, replace the Sensor Circuit Board. If the magnetic
attraction occurs only on one coil for 27 seconds, but
not the other, check for open wire connections at the
purge valve coil, and at the Sensor Board and if the
wiring is not at fault, replace the Sensor Board.
12.9.8 Excess air ow capacity can cause a Humidity
Alarm. If the cause of the humidity alarm is still
unexplained after completing the preceding tests,
increase the System Pressure 1 or 2 PSIG higher to
provide extra purge air in the event that compressor
capacity is exceptional. Call the factory for addtional
instructions to check compressor capacity and
adjustment.
12.9.9 Tower restriction can cause a Humidity
Alarm. If the humidity alarm persists and neither
cycling interruption nor low System Pressure is the
cause, measure the pressure at the test valve at the top
of each desiccant tower with a test gauge (test gauge
range minimum 30 PSIG) for a full minute. For 27
seconds of each minute, the pressure in alternate
towers (purge pressure) should drop to 2.0 PSIG
or less. If the purge pressure is somewhat higher,
increase the System Pressure an equal amount.
To Next Page
Loading...