520 Indoor / 520 Outdoor Service Manual
Ver. 1.00
43
CONFIDENTIAL
Natural
of
Fault
Diagnosis
Checkpoint
・
Fluctuation
of hot water
temperature
4 Fault of PCB in the water heater
[1] No voltage to gas solenoid valve (SV
1
).
Normal: 78 to 100 VDC between COM (blue) & #9 (green)
(during operation)
[2] No voltage to gas solenoid valve (SV
3
).
Normal: 78 to 100 VDC between COM (blue) & #73 (red)
(during operation)
C
5 Gas solenoid valve (SV
1
) fault
[1] Disconnected wiring to gas solenoid valve (SV
1
)
Normal: 1.3 to 1.9 k
Ω
between COM (blue) & #9 (green)
[2] Disconnected wiring to gas solenoid valve (SV
3
)
Normal: 0.9 to 1.7 k
Ω
between COM (blue) & #73 (red)
C
6 Fault of PCB in the water heater
No voltage to water control valve
Normal: 13.0 to 16.0 VDC between (blue-brown)
Normal: ON 12.5 to 16.0 V / OFF 0 to 1 V between (orange-brown)
Normal: 1 VDC less (0
˚
position) between (red-brown)
J
7 Fault of Water control valve
Normal: 0.09 to 0.2 k
Ω
between (red-black)
J
Error Code
Malfunction description
Cancellation method
031
Incorrect dipswitch setting fault
Turn off the power or water supply
Diagnosis
Checkpoint
Check the dipswitch settings on PCB
Error Code
Malfunction description
Cancellation method
101
Warning for the “991” error code
(Refer to section 12-3)
On the PCB, press the INC and DEC
buttons simultaneously for 3 sec. Then
turn the power off.
Diagnosis
Checkpoint
1 Check the gas type of the water heater.
2 Check how long the water heater has been installed and in use.
3 Check the installation location.
4 Check the altitude/elevation of area of where the water heater installed.
5 Check the vent length.
6 Check if there is any blockage in the intake air and/or exhaust.
