Airtek 4087 Walden Avenue, Lancaster, NY 14086 TEL: (716) 685-4040 FAX: (716) 685-1010 E-MAIL: airtek@airtek.com WEB SITE: www.airtek.com
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way to see if the coil is energized is to take a
screwdriver or something metal and touch it to the
screw or post on the top of the coil. When the coil
is energized there is a magnetic field produced
which will pull the metal object to the screw post. If
it is, the coil may be shorted closed, causing the
digital control board to give a constant electric
signal from the K3 relay affixed to the back of the
board. If this is the case replace the control board,
and the coil.
2) If you have determined that the valve is not getting
energized electrically, then the valve may have
malfunctioned mechanically. Determining this is
relatively easy. When the dryer is refrigerating and
the Power Saver Active light is off we know that the
unloader solenoid should be closed. If it has failed
mechanically there will be equal temperature
copper lines in and out of the valve. There is
always hot gas on the incoming side of the
solenoid; therefore it should be hot. If the valve is
closed the copper line on the outgoing side of the
solenoid should be relatively cool. It would be
suggested that you check the copper line just
before it enters the static cooler near the evapora-
tor, due to the fact that some heat may transfer
through the metal of the valve and show hot just on
the out going line of the solenoid. This tempera-
ture can be checked by infrared temperature gun. If
this seems to be the problem the internals of or
the whole valve should be replaced.
If you have determined that the unloader solenoid
is fine the other problem component would be the
compressor. Check the following:
B) Compressor will not start, no hum.
1) Service toggle switch is in off position. Turn on.
(Models SC/CT1500 and up.)
2) Fuse removed or blown. Replace fuse.
3) Overload tripped. Wait 5 to 20 minutes to reset.
Check ambient and inlet air temperatures,
operating pressures and airflow rates against
rated capacities listed, to determine cause of
overload.
4) Loose or improper wiring. Check connections
against schematic. Tighten loose connections.
5) Starter coils open or contact burnt. Replace coils
and/or contact.
C) Compressor will not start, hums, trips overload
protector.
1) Loose or improper wiring.
2) Low line voltage, 10% less of nameplate rating.
Check line voltage with voltmeter. Correct condi-
tion.
3) Start windings open or shorted. Check with
ohmmeter, referring to motor schematic for correct
value. Replace motor.
4) Open or unbalanced phase (3 phase units).
Check phases for equal voltages (+/-10%). Correct
unbalanced or open condition.
5) Relay or contactor not closing. Examine contacts
and coils for burning, opens, shorts or sticking.
Correct conditions.
6) Compressor internal mechanical failure. Loss of
oil may have locked up the compressor. If above
steps do not apply, this may be the cause.
Replace compressor.
D) Unit short-cycles.
1) Motor overload cutting. Check for high head
pressure or air overload, high ambient clogged
condenser.
2) Defective overload protectors. Check currents.
Replace if necessary.
3) Low voltage or 3 phase unbalance. Voltage must
be within 10% on nameplate rating. Correct off
specification conditions.
4) Refrigerant Shortage. Check for leaks. Repair and
recharge.
5) Shortage motor windings. If the dryer begins to
run examine the dew point. If it does not fall to the
dew point set point check the following things.
E) Weak Compressor
1) A refrigeration technician would be needed to
justify a faulty compressor. If the compressor is
running and the freon pressures are somewhat
equalized from the high side of the system to the
low side the compressor is not pumping. The only
cure for this is a replacement compressor. Again,
a refrigeration technician would be needed to
perform the repair.
Diagnostic code “E6”
Shutdown on Low Suction PSI
*
Pressures referenced in this section refer to units
using R-22. For other refrigerants, please refer to
service tag for specifications.
If the suction pressure of the refrigeration system
drops 20 PSI or lower it will break contact through the low-
pressure switch. This in turn breaks power to the refriger-
ant compressor for protection.
To correct this 1. Bypass the compressed air around
the dryer. 2. Based on the size of the unit you will have
either manual resetting pressure switches, or a reset
through the control panel by pressing the mode selection
button off then on again after 10 seconds. If the condition
continues, check the following probable causes:
A) Low Freon - Typically if the unit were low on freon
you would see an “E3” code. However if there was
for some reason a large loss of freon in short time
this could result in a low-pressure cut out. This
condition is usually caused by a large leak due to
a damaged refrigerant line.
1) Some ways of determining a leak is to
physically examine the unit for what may
appear as a puddle or spray of oil. Refrigerant
carries the lubricant for the compressor and
would show up where the leak occurred.
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