520 Indoor / 520 Outdoor Service Manual
Ver. 1.00
48
CONFIDENTIAL
Error Code
Malfunction description
Cancellation method
510
Fault of driving circuit for main gas solenoid
valve (MV, SV
1
,
SV
2
and/or SV
3
)
Turn off the power supply
(The computer checks the condition of the main
gas valve immediately after every operation and
the conditions of the solenoid valves 6 hours
after every operation)
Diagnosis
Checkpoint
1 PCB and/or main gas valve fault
(Refer to section 10-5 & 10-18)
Visual inspection of gas valves: connection/breakage of wires.
Normal: 78 to 100 VDC between COM (blue) & #3 (light blue)
(during operation)
Normal: 78 to 100 VDC between COM (blue) & #9 (green)
(during operation)
Normal: 78 to 100 VDC between COM (blue) & #53 (orange)
(during operation)
Normal: 78 to 100 VDC between COM (blue) & #73 (red)
(during operation)
Visual inspection of PCB: connection/breakage of wires and/or burn marks
on the computer board.
2 Gas solenoid valve fault (MV, SV
1
,
SV
2
and/or SV
3
)
C
Error Code
Malfunction description
Cancellation method
551
Fault of driving circuit for any of the gas
solenoid valves (SV
1
, SV
2
, and/or SV
3
)
Turn off the power supply
(The computer checks the condition of the
solenoid valves 6 hours after every operation)
Diagnosis
Checkpoint
1 PCB and/or gas valve fault (Refer to section 10-5 & 10-18)
Visual inspection of gas valves: connection/breakage of wires.
Normal: 78 to 100 VDC between COM (blue) & #9 (green)
(during operation)
Normal: 78 to 100 VDC between COM (blue) & #53 (orange)
(during operation)
Normal: 78 to 100 VDC between COM (blue) & #73 (red)
(during operation)
Visual inspection of PCB: connection/breakage of wires and/or burn marks
on the computer board.
2 Gas solenoid valve fault (SV
1
, SV
2
, and/or SV
3
)
C
