Troubleshooting; Ignition Control Board: Error Codes; Flash; Flashes - A.O. Smith SERIES 120 Service Handbook

TROUBLESHOOTING

IGNITION CONTROL BOARD: ERROR CODES

The White Rodgers ignition control board will display a flashing error code with an LED
light located on the upper left corner of the Ignition Control Board (Figure 18) when there is
a problem. There is a distinctive pause between a series of on/ off flashes (1 to 8 flashes)
when there is a problem. The following information describes the meaning of these error
"flash" codes and what should be checked and/or repaired. The 5 flash error code is not
used with this application.
NOTE: The Ignition Control Board varies the voltage to the Igniter to decrease wear. Lower
voltage results in a longer life for the Igniter. For this reason, voltage to the Igniter may
vary from 80 VAC to 120 VAC.

1 FLASH

System has locked out after 3 trials for ignition.
1 Check voltage (80-120 VAC) to igniter.
2 Check flame sense rod alignment.
3 Check igniter and flame sense rod wiring.
4 Check flame sense rod for corrosion; clean with steel wool.
5 Check igniter resistance. It should be 11 - 20 ohms.
6 Check ceramic insulator on igniter/flame sensor assembly for cracks. Replace if
damaged.
7 Check manifold gas pressure.
8 Check all molex plug connections; on integrated control, ignition control board, and
between the various components. Check the pin-to-pin contact between plugs; gen tly
wiggle suspected plug connections during operation.

2 FLASHES

Blower Prover Switch circuit was closed during self-diagnostic check at the
beginning of the heat cycle. Contacts should have opened at the end of last heat
cycle. Blower (Draft Inducer) will not start; call for heat "Status" LED will be illuminated on
integrated control.
1 Test continuity of blower prover switch; it should be open in "normal state" (blower not
running - wires removed)
2 Replace blower prover switch if continuity is present between terminals in normal state.
3 Check blower prover switch wiring, making sure that there are no jumpers on blower
prover switch.
TROUBLESHOOTING
Servicing should only be performed by a Qualifi ed Service Agent
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