2 Stage Troubleshooting Codes
Symptom
LED Status
Fault Description
Corrective Actions
Flame sense micro amp signal is minimal
Flame sensor is coated/oxidized
Flame sensor incorrectly positioned in burner
fame
Lazy burner flame due to improper gas
pressure or combustion air
Compare current gas pressure to rating plate and adjust
as needed
Problem with igniter circuit
Check and correct wiring from integrated control module
to igniter
Improperly connected or shorted igniter
Poor unit ground
Igniter relay fault on integrated control module
Check igniter output from control, replace if necessary
High stage pressure switch circuit is closed at
start of heating cycle.
High stage pressure switch contacts sticking
Shorts in pressure switch circuit wiring
Repair short in wiring
Furnace fails to operate on high
stage; furnace operates normally
on low stage
Inspect pressure switch hose, repair/replace if necessary
Inspect flue piping for blockage, proper length, elbows,
and termination
Check induced draft blower performance, correct as
necessary
Tighten or correct wiring connection
Polarity of 115 volt AC is reversed
Correct polarity, check and correct wiring if necessary
Poor unit ground
Verify proper ground, correct if necessary
Gas valve is not energized when it should be
Check wiring in gas valve circuit
External Gas Valve Error
Replace integrated control board
Gas valve is energized when it should not be
Check wiring in gas valve circuit
Internal gas valve error
Replace integrated control board
Furnace fails to operate.
No 115 power to furnace or no 24 volt power
to integrated control module.
Restore high voltage power to furnace and integrated
control module.
Blown fuse or tripped circuit breaker
Correct condition which caused fuse to open, replace
fuse
Integrated control module is non- functional
Replace non-functional integrated control module.
Furnace fails to operate
Grounding fault
Poor neutral connection
Verify neutral wire connection to furnace & continuity to
ground source
Furnace fails to operate
Open roll out switch
Check for correct gas pressure Check for correct burner
alignment
Check for and correct burner restriction
Furnace fails to operate
Ignitor Open
Check for Ignitor wiring.
Replace Damaged Ignitor
Furnace fails to operate
Inducer relay Error
Replace integrated control board
Twinning feature not working
TWIN Error
Check for wiring connections.
Replace integrated control board
Furnace fails to operate
Internal Faults or IRQ Loss in Control Board
Replace integrated control board
Clean flame sensor if coated or oxidized Inspect for
proper flame sensor alignment
Furnace fails to operate
Diagnose and replace shorted igniter as needed Verify
and correct unit ground wiring if needed
None
Integrated control module LED
display provides no signal
TROUBLESHOOTING CHART
Furnace fails to operate
Furnace fails to operate
Furnace fails to operate
Furnace fails to operate on high
stage; furnace operates normally
on low stage
Induced draft blower operating
Diagnose and replace high stage pressure switch if
needed
High stage pressure switch circuit is not
closed
Induced draft blower operating
Normal furnace operation
TROUBLESHOOTING
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