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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the mode selection button to turn the unit off then pressing
it again to turn it on. If the condition is not corrected the unit
will shut down again in 40 minutes.
Reset the unit once more. Wait 5 minutes and check
your superheat. To check the superheat press the hidden
button located between the two mode selection buttons. If
the temperature is not within range, check the following
probable causes:
A) Low Freon Charge
Examine sightglass, if you can see a level or a
flurry of bubbles for a long period of time you may
be low on freon. It is common to see an occa-
sional bubble at times. It is also common to see a
flurry of bubbles when the dryer loads and
unloads.
Another way to check freon level is with an inferred
heat gun to the liquid line receiver if it is not a 1/3
full this may be an indication you are low on freon.
If you are low on freon the unit needs to be leak
checked and charged.
If you are still shutting down on “E3” and your super heat
temperature is within range the probable causes are:
B) Poor Contact of Super Heat Sensing Probe
Locate the superheat-sensing probe, which will be
located next to the thermal expansion valve
sensing bulb. If for some reason it is not tightened
securely to the copper line it will sense a higher
ambient temperature. This will provide a false
reading to the control board of high super heat,
and in turn the unit will shut down “E3”. If the “E3”
probe is loose, tighten copper strap securely for
best results.
C) Defective Super Heat Probe
If the “E3” probe is tightened securely to the
copper line and your super heat is within range
(10º - 25ºF), and your dryer is still shutting down on
“E3”, your probe is defective. To check this,
disconnect power from the unit. Locate the probe
connection (labeled probe 2) and disconnect it
from the board, if it runs fine after this, replace
probe. Reapply power. If it still shuts down on “E3”
after 40 minutes, replace the control board.
D) Expansion Valve Stuck Closed
Test by applying heat (hair dryer) to TXV sensing
bulb located just after the flood level control for
about 30-45 seconds. This should cause the unit
to flood back and lower the super heat. To check
this, take a temperature reading on the suction
accumulator, it should be extremely cold, if it is not,
your expansion valve is stuck closed. Your suction
accumulator normally shows a level based on
temperature of being 1/3 to 1/2 full.
Diagnostic code “E4”
Shutdown on Freeze Protection
Freezing is defined as the point at which the actual
dew point falls to 20ºF or lower. If this condition occurs and
lasts for ten minutes, an “E4” will display and the dryer will
shut down. This will prevent the unit from freezing. Most
importantly it will save the evaporator from developing a
leak due to expansion of moisture which may be present
within the evaporator tubing.
The probable cause of this problem is the unloader
valve failing to open in some matter. To further diagnose the
cause of this failure and to check operation, turn the unit off
then on again after 15 seconds using the Load/Unload
mode. This will clear the diagnostic code and cause the
unit to operate again. When the dew point falls below the
dew point set point the Power Saver Active light should
come on and the following items should be checked:
1) You need to first check the coil of the unloader
valve to ensure that it is functioning. The easiest
way to verify if the coil is energized is to take a
screwdriver and touch it to the screw or post on the
top of the coil. If the coil is energized there will be a
magnetic field pulling the metal to the screw or
post. If the Power Saver Active light is on and there
is no magnetic pull, the coil is not functioning.
2) If you have determined the coil is not functioning
there are two things you must check, Test the coil
electrically for continuity to ensure it is not shorted.
If it is shorted replace the coil. If the coil is not
shorted you need to check the K3 relay on the back
of the control board marked “Unloader”, terminals
9 and 10. There should be a 120V output from this
relay. If there is not replace the board.
3) If the coil is functioning and the dew point contin-
ues to fall, the unloader solenoid is defective. The
internals or the whole valve should be replaced.
Remember all of this must be checked while the unit is
operative and in the unloaded state. The way this is
determined is by the Power Saver Active light being
illuminated.
Diagnostic code “E5”
High Dew Point Shutdown
If the actual dew point on the digital control board
reads 40ºF higher than the dew point set point for 10
minutes, the dryer will shut down and a diagnostic code of
“E5”.
The probable causes for this condition is the unloader
solenoid sticking open, or a weak or defective compressor.
The dryer can be reset by pressing the mode selection
button to turn the unit off, and then pressing it again will turn
the unit back on. If the dew point does not fall check the
following:
A) Unloader valve stuck open.
1) You first need to determine if the unloader valve is
functioning properly. When the dryer is refrigerating
and the Power Saver Active light is off, the unloader
valve should be de-energized and closed. It is
unlikely that the coil is shorted closed but not
impossible. You can check the solenoid electri-
cally to see if it is getting an electric signal. Another
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