Ideal
Ideal Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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F1
Ideal furnace locks out shortly after start; the burner does not light, and the fan may run briefly then stop.
Ignition Lockout / Ignition Failure
F10
Ideal furnace displays F10, with no ignition or immediate lockout after a call for heat.
Ignition Lockout – Repeated Failed Starts
F11
Furnace displays F11; the blower may run continuously, but there is no heating output.
Low-Voltage / Communication Fault
F12
Ideal furnace displays F12; the unit may start but shuts down randomly, sometimes with display flicker.
Power Supply / Voltage Fault
F13
Furnace displays F13, runs briefly then shuts down, and may be associated with condensate issues on condensing Ideal models.
Condensate Drain / Trap Fault
F14
Ideal furnace displays F14, with no ignition or immediate shutdown after the flame is established.
Flame Signal Weak / Unstable Combustion
F15
Furnace displays F15; the blower may run, but the burner does not light, or the unit cycles without heating.
Low Temperature Rise / Inadequate Heating
F16
Ideal furnace displays F16; the unit may overheat or shut down unexpectedly, sometimes with noisy operation.
Fan Speed / Blower Control Fault
F17
Furnace displays F17, with no response to the thermostat, or intermittent operation accompanied by a communication-related error.
External Control / Smart Interface Fault
F18
Ideal furnace displays F18; the unit may lock out after several failed attempts, often in very cold weather.
Frozen or Blocked Flue / Intake
F19
Furnace displays F19, frequent cycling, and may not maintain the set temperature.
Short Cycling / Overheat-Reset Pattern
F2
Ideal furnace attempts to start but shuts down quickly; the fan may run, but there is no sustained flame.
Flame Detection Failure
F20
Ideal furnace shows F20, no ignition, or an immediate lockout with a gas-related warning.
Incorrect Gas Type / Configuration Fault
F3
Furnace will not start; the inducer fan may not run, and F3 is displayed on the Ideal control.
Pressure Switch Open / Airflow Proving Failure
F4
Ideal furnace locks out with F4; the burner shuts down during operation and may cycle on and off frequently.
High Limit / Overheat Trip
F5
Furnace fails to start or shuts down with F5; the fan may run continuously, but there is no heat.
Rollout Switch Trip / Flame Rollout Detected
F6
Ideal furnace shows F6; the inducer runs, but the ignition sequence does not proceed, or the unit cycles without lighting.
Airflow / Fan Proving Fault (Inducer or Combustion Air)
F7
Furnace displays F7; it will not start, and the thermostat appears to call for heat but receives no response.
Thermostat / Control Signal Fault
F8
Ideal furnace shows F8; the blower runs but provides no heat, or there is intermittent heating with a control board error.
Control Board / Internal Electronics Fault
F9
Furnace displays F9, runs briefly then shuts down, and may be accompanied by unusual flame behavior.
Gas Valve / Gas Supply Fault
Symptom
Burner flame appears yellow, lazy, or produces soot; possible smell of exhaust.
Poor Combustion / Incomplete Burning
Symptom
Furnace does not start at all; no fan, no clicking, and no display or indicator lights.
No Power / Dead Furnace
Symptom
Furnace runs but produces no heat; the blower operates, but the supply air is cold.
Burner Not Firing / No Flame
Symptom
Furnace runs for a few minutes, then shuts off; the blower continues to run with no heat.
Overheating / High Limit Cycling
Symptom
Furnace starts, then shuts off after a few seconds; repeated short attempts to ignite occur.
Short Cycling on Ignition / Flame Loss
Symptom
Strong smell of gas near the furnace, especially during or after operation.
Gas Leak / Unsafe Gas Escape
Symptom
The blower fan runs continuously even when the thermostat is not calling for heat.
Stuck Fan Relay / Fan Control Fault
Symptom
The furnace causes strong vibration or rumbling felt throughout the house when running.
Excessive Vibration / Imbalanced Blower
Symptom
The furnace causes the carbon monoxide alarm to activate when running.
Combustion Gas Spillage / Heat Exchanger or Flue Fault
Symptom
The furnace emits a burning smell when first started or after long inactivity.
Dust Burn-Off / Overheating Components
Symptom
The furnace frequently turns on and off in short bursts, and the house temperature fluctuates.
Short Cycling (Thermostat or Sizing Issue)
Symptom
The furnace is very noisy during operation; rattling, banging, or a high-pitched squealing sound may come from the unit.
Mechanical Noise / Vibration Fault
Symptom
The furnace runs, but energy bills are unusually high, and the house still feels cool.
Low Efficiency / Poor Heat Transfer
Symptom
The furnace runs, but some rooms remain cold or airflow is weak at certain registers.
Insufficient Airflow / Distribution Issue
Symptom
The furnace starts normally but shuts down when the blower starts; it may trip the breaker.
Blower Motor Overload / Electrical Fault
Symptom
The furnace will not respond to the thermostat; the thermostat appears to work, but the furnace stays off.
Thermostat Control / Low-Voltage Circuit Fault
Symptom
Visible rust or staining around the burner compartment; possible water inside the combustion area.
Internal Condensate / Heat Exchanger Leak
Symptom
Water leaking from the base of the Ideal furnace or from its internal panels.
Condensate Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| F1 |
Ideal furnace locks out shortly after start; the burner does not light, and the fan may run briefly then stop.
|
Ignition Lockout / Ignition Failure | View Details |
| F10 |
Ideal furnace displays F10, with no ignition or immediate lockout after a call for heat.
|
Ignition Lockout – Repeated Failed Starts | View Details |
| F11 |
Furnace displays F11; the blower may run continuously, but there is no heating output.
|
Low-Voltage / Communication Fault | View Details |
| F12 |
Ideal furnace displays F12; the unit may start but shuts down randomly, sometimes with display flicker.
|
Power Supply / Voltage Fault | View Details |
| F13 |
Furnace displays F13, runs briefly then shuts down, and may be associated with condensate issues on condensing Ideal models.
|
Condensate Drain / Trap Fault | View Details |
| F14 |
Ideal furnace displays F14, with no ignition or immediate shutdown after the flame is established.
|
Flame Signal Weak / Unstable Combustion | View Details |
| F15 |
Furnace displays F15; the blower may run, but the burner does not light, or the unit cycles without heating.
|
Low Temperature Rise / Inadequate Heating | View Details |
| F16 |
Ideal furnace displays F16; the unit may overheat or shut down unexpectedly, sometimes with noisy operation.
|
Fan Speed / Blower Control Fault | View Details |
| F17 |
Furnace displays F17, with no response to the thermostat, or intermittent operation accompanied by a communication-related error.
|
External Control / Smart Interface Fault | View Details |
| F18 |
Ideal furnace displays F18; the unit may lock out after several failed attempts, often in very cold weather.
|
Frozen or Blocked Flue / Intake | View Details |
| F19 |
Furnace displays F19, frequent cycling, and may not maintain the set temperature.
|
Short Cycling / Overheat-Reset Pattern | View Details |
| F2 |
Ideal furnace attempts to start but shuts down quickly; the fan may run, but there is no sustained flame.
|
Flame Detection Failure | View Details |
| F20 |
Ideal furnace shows F20, no ignition, or an immediate lockout with a gas-related warning.
|
Incorrect Gas Type / Configuration Fault | View Details |
| F3 |
Furnace will not start; the inducer fan may not run, and F3 is displayed on the Ideal control.
|
Pressure Switch Open / Airflow Proving Failure | View Details |
| F4 |
Ideal furnace locks out with F4; the burner shuts down during operation and may cycle on and off frequently.
|
High Limit / Overheat Trip | View Details |
| F5 |
Furnace fails to start or shuts down with F5; the fan may run continuously, but there is no heat.
|
Rollout Switch Trip / Flame Rollout Detected | View Details |
| F6 |
Ideal furnace shows F6; the inducer runs, but the ignition sequence does not proceed, or the unit cycles without lighting.
|
Airflow / Fan Proving Fault (Inducer or Combustion Air) | View Details |
| F7 |
Furnace displays F7; it will not start, and the thermostat appears to call for heat but receives no response.
|
Thermostat / Control Signal Fault | View Details |
| F8 |
Ideal furnace shows F8; the blower runs but provides no heat, or there is intermittent heating with a control board error.
|
Control Board / Internal Electronics Fault | View Details |
| F9 |
Furnace displays F9, runs briefly then shuts down, and may be accompanied by unusual flame behavior.
|
Gas Valve / Gas Supply Fault | View Details |
| – |
Burner flame appears yellow, lazy, or produces soot; possible smell of exhaust.
|
Poor Combustion / Incomplete Burning | View Details |
| – |
Furnace does not start at all; no fan, no clicking, and no display or indicator lights.
|
No Power / Dead Furnace | View Details |
| – |
Furnace runs but produces no heat; the blower operates, but the supply air is cold.
|
Burner Not Firing / No Flame | View Details |
| – |
Furnace runs for a few minutes, then shuts off; the blower continues to run with no heat.
|
Overheating / High Limit Cycling | View Details |
| – |
Furnace starts, then shuts off after a few seconds; repeated short attempts to ignite occur.
|
Short Cycling on Ignition / Flame Loss | View Details |
| – |
Strong smell of gas near the furnace, especially during or after operation.
|
Gas Leak / Unsafe Gas Escape | View Details |
| – |
The blower fan runs continuously even when the thermostat is not calling for heat.
|
Stuck Fan Relay / Fan Control Fault | View Details |
| – |
The furnace causes strong vibration or rumbling felt throughout the house when running.
|
Excessive Vibration / Imbalanced Blower | View Details |
| – |
The furnace causes the carbon monoxide alarm to activate when running.
|
Combustion Gas Spillage / Heat Exchanger or Flue Fault | View Details |
| – |
The furnace emits a burning smell when first started or after long inactivity.
|
Dust Burn-Off / Overheating Components | View Details |
| – |
The furnace frequently turns on and off in short bursts, and the house temperature fluctuates.
|
Short Cycling (Thermostat or Sizing Issue) | View Details |
| – |
The furnace is very noisy during operation; rattling, banging, or a high-pitched squealing sound may come from the unit.
|
Mechanical Noise / Vibration Fault | View Details |
| – |
The furnace runs, but energy bills are unusually high, and the house still feels cool.
|
Low Efficiency / Poor Heat Transfer | View Details |
| – |
The furnace runs, but some rooms remain cold or airflow is weak at certain registers.
|
Insufficient Airflow / Distribution Issue | View Details |
| – |
The furnace starts normally but shuts down when the blower starts; it may trip the breaker.
|
Blower Motor Overload / Electrical Fault | View Details |
| – |
The furnace will not respond to the thermostat; the thermostat appears to work, but the furnace stays off.
|
Thermostat Control / Low-Voltage Circuit Fault | View Details |
| – |
Visible rust or staining around the burner compartment; possible water inside the combustion area.
|
Internal Condensate / Heat Exchanger Leak | View Details |
| – |
Water leaking from the base of the Ideal furnace or from its internal panels.
|
Condensate Leak | View Details |
No matching codes found
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