LG GEN2 Series Installation And Operation Manual page 85

Troubleshooting - 4:1 Modulating Furnace
4:1 Modulating Furnace with Stand-Alone Controller Will Not Light
In all cases, verify correct terminals as shown on the unit-specific wiring diagram.
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Furnace Controller Alarm:
'High Temp. Alarm'?
No
Furnace Controller Alarm:
'IG furnace max retry'?
No
Everything is working properly,
consult factory.
Discharge temperature was above high limit control (HLC)
Yes
Pressure switch (PS2) trip due to high discharge temp
(Check pressure at combustion fan pressure tap with furnace running and
compare reading to pressure setting of pressure switches.)
1. If Pressure switch trips at wrong pressure, replace pressure switch.
2. If the combustion fan does not generate enough pressure, consult the
Yes
Furnace has reached its maximum number of automatic error
1. Review alarm history and correct any issues identified
2. Reset the max retry alarm by holding the alarm button on the furnace
controller for 3 seconds. Verify proper furnace operation.
Wait for high limit to cool and reset
factory.
resets