GSI Outdoors PNEG-630 - Manual (Page 61)

Portable Dryer Troubleshooting
60
Air Pressure System
Symptoms: Dryer will indicate a "Loss of Airflow"
negatives for the black probe(-) of your
voltmeter. Some of the terminals that
may be used for the negative(-) are J5-11,
J5-12 or J5-13.
• To check fan #1 for air pressure with a
voltmeter:
1. Turn on the dryer.
2. Place the black probe(negative) of
your voltmeter on J5-11 or J5-12.
3. Place the red probe(positive) of your
voltmeter on J1-13. At this point
there should be zero volts here be-
cause the fan is not running.
4. Turn on the fan and watch your volt-
meter.
• If the air switch is adjusted properly you
should have zero volts across these test
points when you first turn on the fan. Af-
ter the fan has run up to about one half of
its normal operating speed you should see
the voltmeter change from zero volts to 12
volts DC. This also works in reverse when
turning off the fan. After the fan is first
turned off, the voltmeter should still show
12 volts DC until the fan has slowed down
to about one half of its operating speed.
This is because even though the fan is
turned off it is still turning and developing some
pressure in the plenum.
• After turning on a fan the computer must
get a signal from the air pressure switch
telling it that the fan is actually running
and the plenum has been pressurized. If
the switch does not show the air pressure
within 20 seconds a "Loss of Airflow"
shutdown occurs.
Airflow Operation
• This error message indicates that the fan
is running and the air pressure in the ple-
num did not pressurize. First, verify that
the fan is running, and the dryer is full of
grain. There must be grain in the dryer or
no pressure will develop. If the fan does
come on and the dryer is full of grain, but
a "Loss of Airflow" shutdown still occurs,
check the air pressure switch circuit.
• Watching the blue light in the fan switch
is the easiest way to tell if the air pres-
sure switch is sensing air pressure. Each
air pressure switch has a light in the fan
switch that will only come on if air pres-
sure has developed. Turn on the fan and
after it has run up to about one half of its
operating speed the light should go on. If
the fan light is not coming on then the air
pressure circuit is not sensing pressure.
• Try adjusting the air switch on the front
of the plenum to see if it is just out of ad-
justment. Use a straight blade screw-
Troubleshooting: "Loss of Airflow"
• When inspecting the sensor make sure
that the wheel going through the sensor is
positioned in the center and is not touch-
ing either side. If the sensor is scratched
it is either bad or will probably go bad.
driver and turn the adjusting screw coun-
terclockwise. Turning it this way makes
the switch more sensitive to pressure and
will turn on the light easier.
• If adjusting the screw does not solve your
problem consult the layout diagram of the
input/output board. Look for the input for
the problem switch. Example: Fan #1
switch's input is J1-13. This is a 12 volt
DC input and it can be checked with a DC
voltmeter. One of the following conditions
will exist when checking this input.
NO AIR PRESSURE---ZERO VOLTS
HAS AIR PRESSURE---12 VOLTS DC
Remember when checking for 12 volts DC
you should always use one of the DC
Troubleshooting Tips