Drains; Electronic Controls; Factory Assistance; Instructions For Ordering Parts - AirTek SC Series Operator's Manual

Airtek uses standard type valves that can be found in
wholesale houses anywhere. When replacing or repairing
them, remember these points:
* Don't use any TCLE Alco valves. TCLE valves are too
slow.
* Use cross-ambient "C" or liquid "L" charges. Do not
use any pressure limiting or all-purpose "W" charges.
* We recommend that you increase the superheat
setting of the new valve about 5º F from the factory
setting. Turning the stem 2 turns in is about right.
* Position the sensing bulb of the new valve just where
the old one was. It is crucial that the suction line be
clean and the bulb well insulated.
Solenoid Valves: The suction solenoid valve rarely causes
any trouble because the pressure difference across it is
never great. Unloader solenoids operate with greater
differentials and so are more likely to fail. Airtek uses
valves with a rated life of more than two million operations.
When they finally wear out, the usual symptom is failure to
close. The valves can usually be restored by installing a
diaphragm repair kit available from Airtek or the valve's
local distributor.

Drains

The draining of water from the separator is the most crucial
part of the whole process. A complaint of "There's more
water in the air now than there was before the dryer was
installed" is usually a drain problem.
Airtek has a demand operated drain. Operate the drain
manually, push to test. Check the float switch, board or
solenoid valve if not.

Electronic Controls

A dew point temperature controller is used on the Smart
Cycle Dryers. The controller operates the unloader
solenoid, opening it to stop refrigeration if the sensed
temperature goes below the controller setting, usually 36ºF.
The suction solenoid is closed during unloading.
This temperature is sensed by a sensing probe inserted in
one of the evaporator tubes. When air passes over the
probe, the air temperature controls the dew point normally.
When there is little or no air flow, the controller sees the
evaporator temperature, and is able to prevent it from going
below freezing.
The operation of the dew point controller is really simple.
All it does is switch back and forth between opening the
suction line solenoid and closing the unloader and vice
versa. A malfunction of the control system can be sus-
pected if:
1) The suction pressure won't fall when the dew point is
above the set point. You can suspect the unloader
solenoid isn't closing due to a bad diaphragm.
2) The suction pressure won't rise when the dew point
goes below the set point and the controller switches, in
load/unload mode. If the pressure falls rapidly when
the controller switches to "power saver" mode the
unloader solenoid isn't opening. If controller switch
Airtek 4087 Walden Avenue, Lancaster, NY 14086 TEL: (716) 685-4040 FAX: (716) 685-1010 E-MAIL: airtek@airtek.com
doesn't seem to do anything it has to be the controller
or wiring.
3) Suction pressure is very low even when controller
reads over the set point or unit appears to be pumped
down and stopped when it shouldn't be. One or both
solenoids isn't opening when it should.
4) Water freezes in the evaporator causing air pressure
drop (dew point set 34 or higher). This can be partial
failure of unloader solenoid to open, indicated by more
than 60 PSI difference between compressor suction
and discharge.
5) There is erratic or out-of-range indication of dew point.
This is controller or sensor trouble. Consult factory for
details.
6) Dryer won't restart after you stopped it for a test. This
is normal if you stopped when it was unloaded (load-
unload mode) or shut down (start-stop mode). It will
restart when the dew point temperature comes above
the controller setting.
NOTE: For a complete troubleshooting guide, see pages
30-35.
Remember that the easiest way to distinguish between
control and solenoid malfunction is to hold a steel object,
like a pocket screw driver, over the top of the valve's
enclosing tube that sticks out from the coil and feel for
magnification. The magnification means the valve is
energized. If you don't feel it, remember to look at the coil
before suspecting the controller.
The two displays marked AMBIENT or WATER and AIR IN
indicate those temperatures and control only the respective
alarm lights (see ADJUSTMENTS). It is an alarm only and
will not shut your unit down.

Factory Assistance

Please do not hesitate to call the Airtek factory for technical
information and assistance. We have skilled troubleshoot-
ing and engineering personnel who are thoroughly familiar
with the equipment. A short call may save a long trouble-
shooting experience. 1-800-451-6023.

Instructions for Ordering Parts

All parts orders should be placed with your Airtek Dealer.
Should you not know the dealer in your area, contact Airtek
at (800) 451-6023.
When ordering parts, specify dryer model and serial
numbers to insure receiving proper parts (see nameplate
on unit).
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WEB SITE: www.airtek.com