A.O. Smith 110 Indoor Service Manual page 39

Error Code
6 Disconnected/damaged hi-limit switch. (Refer to section 10-11)
V isual inspection: connection/breakage of wires.
11
Normal: 1 Ω or less between blue & blue
7 Inspect flame rod
[1] Check for any soot on the rod.
[2] Check the connection of ground wire; make sure there is firm contact to
Error code is
the ground of the water heater.
shown after
(in this case, the wire is contacted to the manifold surface.)
three failed
[3] PCB fault
During operation: more than 1 μA through the flame rod wire (orange)
attempts at
[4] Flame rod fault
ignition
During operation: more than 1 μA through the flame rod wire (orange)
8 Check if hi-limit switch is properly functioning.
Error Code
Loss of flame
12
1 Check gas supply and pressure
2 PCB fault
Error code is
[1] No voltage to gas main solenoid valve (MV)
shown after
Normal: 78 to 100 VDC between COM (blue) & #3 (light blue)
(during operation)
three failed
[2] No voltage to gas solenoid valve (SV
attempts at
Normal: 78 to 100 VDC between COM (blue) & #53 (orange)
ignition
(during operation)
[3] No voltage to gas proportional valve (VG
Normal: 1 to 15 VDC between white & red (during operation)
3 Gas solenoid fault
[1] Main gas solenoid valve (MV) fault
Normal: 0.9 to 1.3 kΩ between COM (blue) & #3 (light blue)
[2] Gas solenoid valve (SV
Normal: 1.3 to 1.9 kΩ between COM (blue) & #53 (orange)
[3] Gas proportional valve (VG
Normal: 1 to 15 VDC between white & red (during operation)
4 Check for soot on the flame rod
[1] Clean the flame rod
[2] PCB fault
During operation: more than 1 μA through the flame rod wire (orange)
Malfunction description
) fault
2
) fault
0
110 Indoor / 110 Outdoor Service Manual
Diagnosis
Turn off the power or water supply
Diagnosis
(Refer to section 1)
)
2
)
0
39
CONFIDENTIAL
Ver. 1.01
Checkpoint
Cancellation method
Checkpoint
C1
I
C
H1
C
H1
I