Thermo Pride
Thermo Pride 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
Status LED flashes once repeatedly, furnace will not start heating cycle.
Ignition Failure / Lockout
2 FLASHES
Status LED flashes twice repeatedly, furnace will not fire, inducer may run briefly then stop.
Pressure Switch Open / Venting Fault
3 FLASHES
Status LED flashes three times, blower may run but burners do not light.
Pressure Switch Stuck Closed
4 FLASHES
Status LED flashes four times, furnace shuts down shortly after ignition attempt.
Limit Switch Open / Overtemperature Fault
5 FLASHES
Status LED flashes five times, furnace will not start heating cycle, inducer may not run.
Flame Sensed With Gas Valve Off / False Flame Signal
6 FLASHES
Status LED flashes six times, furnace may start but shuts down quickly or will not ignite.
Rollout Switch Open / Flame Rollout Detected
7 FLASHES
Status LED flashes seven times, furnace may lock out, blower may run continuously.
Flame Loss During Run / Re-ignition Failure
8 FLASHES
Status LED flashes eight times, furnace may not respond to thermostat calls.
Low Voltage / Line Polarity / Ground Fault
9 FLASHES
Status LED flashes nine times, furnace may not start or may behave erratically.
Control Board Fault / EEPROM Error
LOCKOUT (SLOW FLASH)
LED flashes slowly indicating soft or hard lockout, furnace will not attempt ignition until reset.
Ignition Lockout After Repeated Failures
NO LED
No LED lights on the control board, furnace completely dead.
No Power to Furnace
STEADY ON
Status LED is solid on with no flashing pattern, furnace not responding to thermostat.
Normal Power / No Call for Heat or Board Idle
Symptom
Furnace blower runs continuously even when there is no call for heat or fan from the thermostat.
Stuck Fan Relay or Open Limit Circuit
Symptom
Furnace blower starts and stops repeatedly without any heat call (fan cycling by itself).
Fan Control or Limit Sensor Drift
Symptom
Furnace blower starts but burners never ignite; you hear no inducer motor.
Inducer Motor Not Starting
Symptom
Furnace cabinet sweats or shows condensation on the outside during operation.
Condensation / Temperature Differential Issue
Symptom
Furnace cycles on and off rapidly at the thermostat (clicking) but burners do not stay lit.
Thermostat or Low-Voltage Control Issue
Symptom
Furnace emits a strong gas smell when attempting to ignite.
Gas Leak or Failed Ignition
Symptom
Furnace frequently trips the household circuit breaker.
Electrical Overload or Short Circuit
Symptom
Furnace ignites but makes a roaring or rumbling noise during operation.
Combustion Instability
Symptom
Furnace inducer motor runs but burners do not light; you hear clicking or see ignitor glow but no flame.
No Gas Flow to Burners
Symptom
Furnace is very loud at the return grille, with whistling or roaring air noise.
Return Air Restriction or Undersized Duct
Symptom
Furnace leaks water around the base or inside the blower compartment.
Condensate Drain Blockage (Condensing Models)
Symptom
Furnace makes loud banging or booming noise at startup.
Delayed Ignition / Burner Light-off Problem
Symptom
Furnace produces a high-pitched whine or squeal during operation.
Blower or Inducer Motor Bearing Wear
Symptom
Furnace rattles or vibrates loudly when running.
Cabinet Vibration / Loose Components
Symptom
Furnace runs but does not produce enough heat; home never reaches set temperature.
Underfiring / Low Heat Output
Symptom
Furnace runs but some rooms are too hot while others are too cold.
Airflow Imbalance / Duct Distribution Issue
Symptom
Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.
Short Cycling Due to Overheating or Oversizing
Symptom
Furnace starts normally but shuts off when the blower comes on.
Flame Disturbance Due to Airflow
Symptom
Furnace starts then shuts off within 30 seconds; burners light but go out quickly.
Flame Sensing Failure
Symptom
Furnace will not start after a power outage.
Control Reset / Low Voltage Recovery Issue
Symptom
Hot surface ignitor does not glow during ignition sequence.
Ignitor Circuit Failure
Symptom
Strong burning or electrical smell when furnace runs.
Overheating Components or Electrical Fault
Symptom
Thermostat calls for heat but furnace only clicks and never starts inducer or blower.
Control Board Relay or Safety Circuit Open
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 1 FLASH |
Status LED flashes once repeatedly, furnace will not start heating cycle.
|
Ignition Failure / Lockout | View Details |
| 2 FLASHES |
Status LED flashes twice repeatedly, furnace will not fire, inducer may run briefly then stop.
|
Pressure Switch Open / Venting Fault | View Details |
| 3 FLASHES |
Status LED flashes three times, blower may run but burners do not light.
|
Pressure Switch Stuck Closed | View Details |
| 4 FLASHES |
Status LED flashes four times, furnace shuts down shortly after ignition attempt.
|
Limit Switch Open / Overtemperature Fault | View Details |
| 5 FLASHES |
Status LED flashes five times, furnace will not start heating cycle, inducer may not run.
|
Flame Sensed With Gas Valve Off / False Flame Signal | View Details |
| 6 FLASHES |
Status LED flashes six times, furnace may start but shuts down quickly or will not ignite.
|
Rollout Switch Open / Flame Rollout Detected | View Details |
| 7 FLASHES |
Status LED flashes seven times, furnace may lock out, blower may run continuously.
|
Flame Loss During Run / Re-ignition Failure | View Details |
| 8 FLASHES |
Status LED flashes eight times, furnace may not respond to thermostat calls.
|
Low Voltage / Line Polarity / Ground Fault | View Details |
| 9 FLASHES |
Status LED flashes nine times, furnace may not start or may behave erratically.
|
Control Board Fault / EEPROM Error | View Details |
| LOCKOUT (SLOW FLASH) |
LED flashes slowly indicating soft or hard lockout, furnace will not attempt ignition until reset.
|
Ignition Lockout After Repeated Failures | View Details |
| NO LED |
No LED lights on the control board, furnace completely dead.
|
No Power to Furnace | View Details |
| STEADY ON |
Status LED is solid on with no flashing pattern, furnace not responding to thermostat.
|
Normal Power / No Call for Heat or Board Idle | View Details |
| – |
Furnace blower runs continuously even when there is no call for heat or fan from the thermostat.
|
Stuck Fan Relay or Open Limit Circuit | View Details |
| – |
Furnace blower starts and stops repeatedly without any heat call (fan cycling by itself).
|
Fan Control or Limit Sensor Drift | View Details |
| – |
Furnace blower starts but burners never ignite; you hear no inducer motor.
|
Inducer Motor Not Starting | View Details |
| – |
Furnace cabinet sweats or shows condensation on the outside during operation.
|
Condensation / Temperature Differential Issue | View Details |
| – |
Furnace cycles on and off rapidly at the thermostat (clicking) but burners do not stay lit.
|
Thermostat or Low-Voltage Control Issue | View Details |
| – |
Furnace emits a strong gas smell when attempting to ignite.
|
Gas Leak or Failed Ignition | View Details |
| – |
Furnace frequently trips the household circuit breaker.
|
Electrical Overload or Short Circuit | View Details |
| – |
Furnace ignites but makes a roaring or rumbling noise during operation.
|
Combustion Instability | View Details |
| – |
Furnace inducer motor runs but burners do not light; you hear clicking or see ignitor glow but no flame.
|
No Gas Flow to Burners | View Details |
| – |
Furnace is very loud at the return grille, with whistling or roaring air noise.
|
Return Air Restriction or Undersized Duct | View Details |
| – |
Furnace leaks water around the base or inside the blower compartment.
|
Condensate Drain Blockage (Condensing Models) | View Details |
| – |
Furnace makes loud banging or booming noise at startup.
|
Delayed Ignition / Burner Light-off Problem | View Details |
| – |
Furnace produces a high-pitched whine or squeal during operation.
|
Blower or Inducer Motor Bearing Wear | View Details |
| – |
Furnace rattles or vibrates loudly when running.
|
Cabinet Vibration / Loose Components | View Details |
| – |
Furnace runs but does not produce enough heat; home never reaches set temperature.
|
Underfiring / Low Heat Output | View Details |
| – |
Furnace runs but some rooms are too hot while others are too cold.
|
Airflow Imbalance / Duct Distribution Issue | View Details |
| – |
Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.
|
Short Cycling Due to Overheating or Oversizing | View Details |
| – |
Furnace starts normally but shuts off when the blower comes on.
|
Flame Disturbance Due to Airflow | View Details |
| – |
Furnace starts then shuts off within 30 seconds; burners light but go out quickly.
|
Flame Sensing Failure | View Details |
| – |
Furnace will not start after a power outage.
|
Control Reset / Low Voltage Recovery Issue | View Details |
| – |
Hot surface ignitor does not glow during ignition sequence.
|
Ignitor Circuit Failure | View Details |
| – |
Strong burning or electrical smell when furnace runs.
|
Overheating Components or Electrical Fault | View Details |
| – |
Thermostat calls for heat but furnace only clicks and never starts inducer or blower.
|
Control Board Relay or Safety Circuit Open | View Details |
No matching codes found
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