ADC AD-464 service manual

c)The burner controller module (BCM) checks that ALL of the dryer’s safety circuits are closed (terminal #7 of the [BCM]). If this is the case, then the green “operating interlocks” L.E.D. (light emitting diode) on the BCM will light. If a safety switch is open, the green L.E.D. will not light, and the red “SYSTEM UNSAFE” L.E.D. will light. The ignition sequence will stop.

If ALL safety switches are closed, the BCM will start the burner fan motor (BCM terminal #8).

The BCM waits 10-seconds to allow the blower motor to get up to speed, and then checks that the burner fan combustion air switch (BCM terminal #6) circuit is closed. If this circuit is open during the drying cycle, the “Air Failure” L.E.D. will light. The gas valve will close, and a “HEATER FAULT” message will be displayed.

In order to prevent this air switch from being jumped out, the BCM checks to insure that this circuit is open prior to start-up, then “SYSTEM UNSAFE” L.E.D. will light.

If the air flow switch closes after the burner fan is turned on, the pilot solenoid valve (BCM terminal #3) is opened for ten (10) seconds, and a spark is produced (BCM terminal #4) by the burner spark plug, igniting the pilot flame.

The flame rod, which extends into the pilot flame, has 300 VAC on it from the BCM (terminal #S1). The flame lets the current flow from the flame rod to ground, which is then converted to 3 to 11 volts DC by the BCM. The “flame signal” L.E.D. on the BCM lights up.

The spark plug will turn off 1.5-seconds after the pilot flame is detected. If the pilot flame should fail during the ten (10) seconds period that the pilot solenoid is open. The BCM will reenergize the spark. If the pilot flame is not established at the end of this 10-second period, the system will lock out and the “FLAME FAILURE” L.E.D. will light.

The 10-second period when the pilot solenoid opens and a spark is produced is called the trial-for- ignition (TFI) time. It is selected at either 5-seconds or 10-seconds by a dip switch located on the back cover of the BCM.

The 3 volt DC to 11 volt DC signal from the flame rod to the BCM can be measured by;

(1)Closing the manual shut-off valve in the main gas line to the burner. Leave the pilot manual valve open.

(2)Push the Test and Reset button on the cover of the burner control module in to the “test” position.

(3)Start a drying cycle...

The burner controller module (BCM) will halt the ignition sequence after the pilot is ignited. The pilot flame should be about the size of a tennis ball and should make the flame cord red hot.

(4)Insert the positive probe of a DC Volt Meter in to the “flame signal” port on the cover of the burner controller module (BCM). Connect the negative probe to ground.

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