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