Fault Analysis Of Error Code - A.O. Smith 910 Installation Manual And Owner's Manual

If the error code is displayed on the computer board of the water heater or the controller, please check
the following. After checking, consult with the manufacturer.
Error
Malfunction
description
code
031 Incorrect DIP
switch setting
101 Warning for the
"991" error code
Ignition failure
111*
Loss of flame
121*
311* Outlet thermistor
failure
321* Inlet thermistor
failure
Mixing thermistor
331*
failure
391* Air-fuel ratio rod
failure
441* Flow sensor
failure (Easy-Link
System only)
510 Abnormal main
gas valve
Abnormal gas
551
solenoid valve
*These error codes will be cleared when water flow stops.
-Fault Analysis of Error Codes-
Check the DIP switches settings on the PCB (Part #701).
Check the gas type of the water heater matches the gas supplied to it.
Check if there is any blockage in the intake air and/or exhaust.
If the water heater is installed as a direct-vent system, check whether there is
enough distance between the intake air terminal and the exhaust terminal.
Check if there is grease and/or dirt in the burner (Part #101) and the fan
motor (Part #416), especially if the water heater has been installed in a
contaminated area.
Check the DIP switches match gas type of unit.
Check the manifold pressure at Max. and Min.
Check the proportional gas valve hose.
Check if the Hi-limit switch (Part #403) is properly functioning.
Check for connection/breakage of wires, burn marks on the computer
board (Part #701), and/or soot on the flame rod (Part #103).
Check if there is a buzzing spark ignition sound coming from the burner
(Part #101) when the water heater prepares for combustion.
Listen for the double "clunk" sound coming from gas valve assembly
(Part#114) when the water heater goes into combustion.
Check if there is leaking from the heat exchanger (Part #401).
Check that the gas is turned on.
Check the gas supply.
Check if the Hi-limit switch (Part #403) is functioning properly.
Check for connection/breakage of wires, burn marks on the computer
board (Part #701), and/or soot on the flame rod (Part #103).
Check if there is leaking from the heat exchanger (Part #401).
Check gas supply
Check for connection/breakage of wires and/or debris on thermistor.
Check the resistance.
Check for connection/breakage of wires and/or soot on the AFR rod.
Check for connection/breakage of wires and/or debris on the flow sensor
impeller.
Check that the water isolation valves are open.
Check inlet water filter for debris.
Check for connection/breakage of wires and/or burn marks on the com-
puter board.
Check for signs of vent corrosion.
Check gas valve contacts and gas valve wire harness connections for signs
of rust or corrosion.
Check for connection/breakage of wires and/or burn marks on the com-
puter board.
Check gas valve contacts and gas valve wire harness connections for signs
of rust or corrosion.
44
Page
Diagnosis