8. Troubleshooting
*In a quick connect multi-system, "F##"(except F76) indicates an error code from the secondary unit (unit without a remote).
This error code is not mentioned in the flowchart.
Note 1)
Note 1)
Note 1)
Flame rod circuit abnormality
(Detection of flame when no
flame is present)
Check for abnormal combustion.
Check flue for blockage or obstruction.
Check for abnormal combustion.
Check flue and air inlet for blockage or obstruction.
Check connection from remote controller to circuit board.
Check remote controller and circuit board for damage.
Check for proper setting of maintenance writers on circuit board.
Check the circuit board (microcomputer) for damage. Check the
dip switch settings.
(ex.high elevation, vent length, etc.).
Combustion abnormality
(Unit shuts off)
Remote controller transmission
abnormality
Circuit board setting abnormality
(Dip switch setting, etc.)
Combustion abnormality
(Warning indication)
760
(F) 90
(F) 73
Check that the main flow control valve is functioning ( ).
Check for improper connection of the valve.
Check for damage to the gas solenoid valve drive circuit on the
circuit board.
Measure the resistance through the inlet thermistor ( ).
Check for an open or short circuit.
Check for improper connection of inlet thermistor.
Measure the resistance through the outlet thermistor ( ).
Check for proportional gas valve trouble ( ).
Check for abnormal combustion.
Check flue for blockage or obstruction.
Diagnosis Point (Trouble Point)
Flame rod does not detect flame
(Flame fault detection)
Outlet thermistor abnormality
Main flow control valve
abnormality
Circuit board abnormality
Heat exchanger thermistor
abnormality
Failure of gas solenoid valve
(other than drive circuit)
Gas solenoid valve drive circuit
abnormality
(F) 72
(F) 71
(F) 70
Fan motor abnormality
(F) 61
(F) 65
(F) 33
Circuit board failure
Air inlet thermistor abnormality
High limit switch triggered
Abnormally high output
temperature
Overheat Prevention Device
(Thermal Fuse) triggered
Inlet thermistor abnormality
(F) 32
(F) 31
(F) 30
(F) 16
(F) 14
Ignition failure
(Initial flame fault detection)
Combustion abnormality
(BTU Drop)
(Unit Continues Working)
The predetermined service period has been reached. Flush the
heat exchanger and/or service the water treatment device.
Service reminder
(F) 12
(F) 11
Display
Description
Measure the current from the flame rod when there is no flame
( ).
Check for a ground fault.
Check the gas supply piping and pressure. Check for igniter
spark ( ). Check gas solenoid valves ( ).
Check flame rod ( ). Check ground, paying special attention to
the ground connection to the circuit board.
Check for accidental extinction of the flame. Check for abnormal
combustion. Check gas solenoid valves. Check flame rod ( ).
Check ground, especially on circuit board.
Check for melting or damage to the thermal fuse ( ).
Check for improper connection of thermal fuse.
Check if high limit switch is triggered ( ).
Check for improper connection of high limit switch.
Measure the resistance through the air inlet thermistor ( ).
Check for an open or short circuit.
Check for improper connection of air inlet thermistor.
Measure the resistance through the heat exchanger thermistor
( ). Check for an open or short circuit.
Check for improper connection of heat exchanger thermistor.
Exhaust thermistor abnormality
(F) 35
Measure the resistance through the exhaust thermistor ( ).
Check for an open or short circuit.
Check for improper connection of exhaust thermistor.
Check that the fan is rotating and check the pulse frequency from
the fan rotational frequency sensor ( ). Check for improper
connection of the fan. Check voltage from circuit board.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, refer to the "Water
Treatment" section.
Remarks
Measure the resistance through the outlet thermistor ( ).
Check for an open or short circuit.
Check for improper connection of outlet thermistor.
(F) 51
Check for proper connection of the gas solenoid valves.
Check for damage to the gas solenoid valve connections.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to
be disconnected and then reconnected.
Check for abnormal combustion. Check flue for blockage or
obstruction. Check that flame ignites all across the burner.
Combustion abnormality
(Unit shuts off)
1
(F) 99
Check gas type
Improper gas type
(F) 91
Check for abnormal combustion ( ).
Exhaust temperature is too high
(F) 94
(F) 20
Condensate trap clogging
Check if the drain line is clogged or frozen ( ).
(F) 29
(F) 10
(F) 05
Note 1)
Check for proper connection of quick connect cord.
Multi-system communication
error
F76
6
4
15
18
17
5
6
8
2
9
10 11
16
16
12
,
3
1
,
4
1
5
1
7
8
Error Codes and Checkpoints
<EN18WI30LS / EP18WI30LS>
19
Summary of Contents for EN18WI30LS
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