Armstrong Air
Armstrong Air Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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1 FLASH
Furnace will not start; status LED flashes 1 time repeatedly on Armstrong Air control board.
Ignition Failure / Lockout
2 FLASH
Furnace attempts to start but shuts down; status LED flashes 2 times repeatedly on Armstrong Air furnace control board.
Pressure Switch Stuck Closed
3 FLASH
Furnace starts inducer but does not ignite; LED flashes 3 times repeatedly on Armstrong Air control board.
Pressure Switch Stuck Open
4 FLASH
Burners ignite then shut off quickly; LED flashes 4 times repeatedly on Armstrong Air furnace board.
Open High Limit Switch
5 FLASH
Furnace cycles on and off; LED flashes 5 times repeatedly on Armstrong Air control board.
Flame Sensed with Gas Valve Off (Flame Rollout or Stuck Gas Valve)
6 FLASH
Furnace will not start; LED flashes 6 times repeatedly on Armstrong Air furnace board.
Soft Lockout / Reversed Line Polarity or Ground Fault
7 FLASH
Furnace starts but shuts down; LED flashes 7 times repeatedly on Armstrong Air control board.
Flame Sense Failure
8 FLASH
Furnace will not start; LED flashes 8 times repeatedly on Armstrong Air furnace board.
Low Flame Sense or Ignition Lockout
9 FLASH
Furnace does not respond to thermostat; LED flashes 9 times repeatedly on Armstrong Air control board.
Incorrect Line Voltage or Grounding / Polarity Error
E0
Armstrong Air communicating furnace thermostat or control displays E0; system may not respond to commands.
Communication Error Between Thermostat and Furnace Control
E1
Armstrong Air communicating thermostat displays E1; furnace may shut down or not respond.
Indoor Temperature Sensor Fault
E2
Armstrong Air communicating thermostat displays E2; system may operate erratically.
Outdoor Temperature Sensor Fault
E3
Armstrong Air communicating thermostat displays E3; furnace may not modulate correctly.
Supply Air Temperature Sensor Fault
E4
Armstrong Air communicating thermostat displays E4; system may shut down or limit capacity.
Return Air Temperature Sensor Fault
E5
Armstrong Air communicating thermostat displays E5; furnace may not respond to staging commands.
Communication Error with Furnace Module
FUSE BLOWN
Low-voltage fuse on Armstrong Air furnace control board repeatedly blows; LED may be off or show intermittent codes.
24V Short Circuit
NO LED
No LED lights on Armstrong Air furnace control board; furnace completely dead and unresponsive.
No Power to Furnace
STEADY ON
Status LED on Armstrong Air furnace control board is solid ON with no flashing; furnace may or may not operate.
Normal Operation or No Fault Indicated
Symptom
Furnace blower runs continuously even when there is no call for heat or cool.
Blower Stuck in Fan-On Mode
Symptom
Furnace blower starts and stops repeatedly without burner ignition; cool air may blow briefly.
Blower Control or Limit Cycling Without Heat
Symptom
Furnace frequently trips the household circuit breaker.
Overcurrent / Electrical Short
Symptom
Furnace ignites but shuts off when blower starts; LED may show flame sense issues.
Flame Disturbance by Airflow
Symptom
Furnace ignites but some burners do not light, causing uneven heating and possible flame rollout trips.
Partial Burner Ignition / Crossover Failure
Symptom
Furnace is running but there is a strong burning or electrical smell in the home.
Overheating Components or Electrical Fault
Symptom
Furnace is very loud at return grille; whistling or roaring sound when running.
Return Air Restriction or Undersized Return
Symptom
Furnace makes loud booming or delayed ignition noise when burners light.
Delayed Ignition
Symptom
Furnace operates but some rooms are too hot while others are too cold.
Air Distribution Imbalance
Symptom
Furnace produces a loud high-pitched whine or rumble during operation.
Inducer or Blower Noise
Symptom
Furnace produces noticeable vibration and rattling noises through the ductwork.
Mechanical Vibration / Loose Components
Symptom
Furnace runs but carbon monoxide detector in the home alarms during operation.
Combustion / Venting Problem
Symptom
Furnace runs but does not produce enough heat; home feels cool even though furnace cycles normally.
Underfiring or Low Heat Output
Symptom
Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.
Short Cycling Due to Overheating or Control Issues
Symptom
Furnace starts but shuts down after a few seconds; LED may show flame-related codes intermittently.
Flame Lift-Off or Unstable Flame
Symptom
Furnace starts normally but shuts down after 30–60 seconds with no obvious error code; blower may or may not start.
Rollout or Auxiliary Limit Trip
Symptom
Furnace will not start at all, but LED shows normal power; thermostat appears to be working.
No Call for Heat Reaching Furnace
Symptom
Water dripping from PVC vent pipe joints or from the furnace flue connection.
Flue Condensation Leak
Symptom
Water leaking around the base of the Armstrong Air high-efficiency furnace.
Condensate Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 1 FLASH |
Furnace will not start; status LED flashes 1 time repeatedly on Armstrong Air control board.
|
Ignition Failure / Lockout | View Details |
| 2 FLASH |
Furnace attempts to start but shuts down; status LED flashes 2 times repeatedly on Armstrong Air furnace control board.
|
Pressure Switch Stuck Closed | View Details |
| 3 FLASH |
Furnace starts inducer but does not ignite; LED flashes 3 times repeatedly on Armstrong Air control board.
|
Pressure Switch Stuck Open | View Details |
| 4 FLASH |
Burners ignite then shut off quickly; LED flashes 4 times repeatedly on Armstrong Air furnace board.
|
Open High Limit Switch | View Details |
| 5 FLASH |
Furnace cycles on and off; LED flashes 5 times repeatedly on Armstrong Air control board.
|
Flame Sensed with Gas Valve Off (Flame Rollout or Stuck Gas Valve) | View Details |
| 6 FLASH |
Furnace will not start; LED flashes 6 times repeatedly on Armstrong Air furnace board.
|
Soft Lockout / Reversed Line Polarity or Ground Fault | View Details |
| 7 FLASH |
Furnace starts but shuts down; LED flashes 7 times repeatedly on Armstrong Air control board.
|
Flame Sense Failure | View Details |
| 8 FLASH |
Furnace will not start; LED flashes 8 times repeatedly on Armstrong Air furnace board.
|
Low Flame Sense or Ignition Lockout | View Details |
| 9 FLASH |
Furnace does not respond to thermostat; LED flashes 9 times repeatedly on Armstrong Air control board.
|
Incorrect Line Voltage or Grounding / Polarity Error | View Details |
| E0 |
Armstrong Air communicating furnace thermostat or control displays E0; system may not respond to commands.
|
Communication Error Between Thermostat and Furnace Control | View Details |
| E1 |
Armstrong Air communicating thermostat displays E1; furnace may shut down or not respond.
|
Indoor Temperature Sensor Fault | View Details |
| E2 |
Armstrong Air communicating thermostat displays E2; system may operate erratically.
|
Outdoor Temperature Sensor Fault | View Details |
| E3 |
Armstrong Air communicating thermostat displays E3; furnace may not modulate correctly.
|
Supply Air Temperature Sensor Fault | View Details |
| E4 |
Armstrong Air communicating thermostat displays E4; system may shut down or limit capacity.
|
Return Air Temperature Sensor Fault | View Details |
| E5 |
Armstrong Air communicating thermostat displays E5; furnace may not respond to staging commands.
|
Communication Error with Furnace Module | View Details |
| FUSE BLOWN |
Low-voltage fuse on Armstrong Air furnace control board repeatedly blows; LED may be off or show intermittent codes.
|
24V Short Circuit | View Details |
| NO LED |
No LED lights on Armstrong Air furnace control board; furnace completely dead and unresponsive.
|
No Power to Furnace | View Details |
| STEADY ON |
Status LED on Armstrong Air furnace control board is solid ON with no flashing; furnace may or may not operate.
|
Normal Operation or No Fault Indicated | View Details |
| – |
Furnace blower runs continuously even when there is no call for heat or cool.
|
Blower Stuck in Fan-On Mode | View Details |
| – |
Furnace blower starts and stops repeatedly without burner ignition; cool air may blow briefly.
|
Blower Control or Limit Cycling Without Heat | View Details |
| – |
Furnace frequently trips the household circuit breaker.
|
Overcurrent / Electrical Short | View Details |
| – |
Furnace ignites but shuts off when blower starts; LED may show flame sense issues.
|
Flame Disturbance by Airflow | View Details |
| – |
Furnace ignites but some burners do not light, causing uneven heating and possible flame rollout trips.
|
Partial Burner Ignition / Crossover Failure | View Details |
| – |
Furnace is running but there is a strong burning or electrical smell in the home.
|
Overheating Components or Electrical Fault | View Details |
| – |
Furnace is very loud at return grille; whistling or roaring sound when running.
|
Return Air Restriction or Undersized Return | View Details |
| – |
Furnace makes loud booming or delayed ignition noise when burners light.
|
Delayed Ignition | View Details |
| – |
Furnace operates but some rooms are too hot while others are too cold.
|
Air Distribution Imbalance | View Details |
| – |
Furnace produces a loud high-pitched whine or rumble during operation.
|
Inducer or Blower Noise | View Details |
| – |
Furnace produces noticeable vibration and rattling noises through the ductwork.
|
Mechanical Vibration / Loose Components | View Details |
| – |
Furnace runs but carbon monoxide detector in the home alarms during operation.
|
Combustion / Venting Problem | View Details |
| – |
Furnace runs but does not produce enough heat; home feels cool even though furnace cycles normally.
|
Underfiring or Low Heat Output | View Details |
| – |
Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.
|
Short Cycling Due to Overheating or Control Issues | View Details |
| – |
Furnace starts but shuts down after a few seconds; LED may show flame-related codes intermittently.
|
Flame Lift-Off or Unstable Flame | View Details |
| – |
Furnace starts normally but shuts down after 30–60 seconds with no obvious error code; blower may or may not start.
|
Rollout or Auxiliary Limit Trip | View Details |
| – |
Furnace will not start at all, but LED shows normal power; thermostat appears to be working.
|
No Call for Heat Reaching Furnace | View Details |
| – |
Water dripping from PVC vent pipe joints or from the furnace flue connection.
|
Flue Condensation Leak | View Details |
| – |
Water leaking around the base of the Armstrong Air high-efficiency furnace.
|
Condensate Leak | View Details |
No matching codes found
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