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2. Troubleshooting/System Detailed Diagnosis
When the dryer calls for heat, 24 VAC from the step down transformer is applied to the "TH" and "GND"
terminals of the DSI module. The DSI module L.E.D. (light emitting diode) indicator will light "red" (for
up to approximately 1.5 seconds [prepurge]) then the L.E.D. indicator will light "green"; the gas valve will
be energized, and the spark burst will be evident (on) for approximately 8 seconds at the tip of the electrode
flame-probe assembly. Flame should now be established and confirmed. If a flame
is not sensed and
confirmed by the ignitor and flame-probe sensor after the approximate 8 second spark burst, the DSI module
will go into the "LOCK-OUT" mode and the L.E.D. will light "red" continuously. THERE ARE NO
RETRIES.
NOTE: To reset the DSI module if it is in the "LOCK-OUT" mode, open and close the main
door, then restart the dryer.
If a flame has been established/confirmed and then lost, the DSI module L.E.D. indicator will continue to
light "green" and immediately a spark will be evident (on) for approximately 8 seconds. The flame should
now be established/confirmed. If a flame is not sensed/confirmed by the ignitor/flame-probe sensor after
the approximate 8 second spark burst, the DSI module will go into the "LOCK-OUT" mode and the L.E.D.
will light "red" continuously. THERE ARE NO RETRIES.
NOTE: To reset the DSI module if it is in the "LOCK-OUT" mode, open and close the main
door, then restart the dryer.
a. System Diagnosis
1) Gas Pressure
A gas pressure test should be taken at the gas valve
pressure tap provided on every gas valve to assure
that the water column (W.C.) pressure is correct
and consistent.
There are two (2) types of devices commonly used
to measure water column (W.C.) pressure. They
are the spring and mechanical type gauge and the
water column test gauge (manometers). The use of
the spring and mechanical type gauges is NOT
RECOMMENDED because they are not
always accurate. The preferred type of gauge is
the manometer because it is a simple device to use
and is highly accurate. A manometer is simply a
glass or transparent plastic tube with a scale
graduated in inches. When it is filled with water
and pressure is applied, the water in the tube rises,
showing the exact water column (W.C.) pressure.
WARNING: Test ALL connections for leaks by
brushing on a soapy water solution.
NEVER TEST FOR LEAKS WITH A
FLAME!