Checking Flame Sensor - Goodman GMES8 U Series Service And Troubleshooting

SERVICING
1. Check for 120 volts from Line 1 (Hot) to Line 2 (Neutral)
at the ignition control. No voltage, check the door switch
connections and wire harness for continuity.
2. Check for 24 volts from W to C terminal on the ignition
control. No voltage. Check transformer, room thermostat,
and wiring.
If you have 24 volts coming off the transformer but receive
approximately 13 volts on the terminal board between (C)
and (R), check for blown fuse.
3. Check for 120 volts to the induced draft blower by
measuring voltage between Pin 4 & 5 (black & white wire
on 5 pin connector.)
4. If voltage is present in Steps 1 through 3 and the induced
draft blower is operating, check for 120 volts to the ignitor
during the preheat cycle.
5. After the ignitor warmup time, begin checking for 24 volts
to the gas valve. Voltage will be present for seven seconds
only if proof of flame has been established.

CHECKING FLAME SENSOR

HIGH VOLTAGE
D ALL
ISCONNECT POWER BEFORE SERVICING OR
M
INSTALLING THIS UNIT. ULTIPLE POWER SOURCES MAY
F
BE PRESENT. AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
1. Disconnect the yellow flame sensor wire from the sensor
2. Connect a micro-amp meter in series with this wire and
the sensor terminal.
3. Place the unit into a heating cycle.
L
INE VOLTAGE NOW PRESENT
4. As soon as flame is established a micro-amp reading
should be evident once proof of flame (micro-amp
reading) is established, the hot surface ignitor will be de-
energized.
5. The Integrated Ignition controls will have 3-10 uAmps.
1-3 uAmps is considered low and will flash 1 amber light.
Anything below 1 uAmps and the unit will shut down. If
the micro-amp reading is less than the minimum specified,
check for high resistance wiring connections, sensor to
burner gap, dirty flame sensor, or poor grounding.
6. If absolutely no reading, check for continuity on all
components and if good - replace ignition control module.
NOTE: Contaminated fuel or combustion air can create a
nearly invisible coating on the flame sensor. This coating
works as an insulator causing a loss in the flame sense signal.
If this situation occurs the flame sensor must be cleaned with
steel wool.
WARNING
WARNING
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