Troubleshooting Chart
| Symptoms of Abnormal | Associated | Fault Description(s) | Possible Causes | Corrective Action | Cautions and Notes | |
| Operation | LED Code2 | |||||
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| • Circulator blower runs |
| • Primary limit |
| • Insufficient conditioned air | • Check filters and | • Turn power OFF |
| continuously. No furnace | 4 | circuit is open. |
| over the heat exchanger. | ductwork for blockage. | prior to repair. |
| operation. |
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| Blocked filters, restrictive | Clean filters or remove | • See Product Data |
| • Integrated control module | 4 FLASHES |
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| ductwork, improper | obstruction. | Bulletin for |
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| circulator blower speed, | • Check circulator blower | |||
| diagnostic LED is flashing |
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| allowable rise | ||
| FOUR (4) flashes. |
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| or failed circulator blower. | speed and performance. | range and proper |
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| • Flame rollout. | Correct speed or replace | circulator speed. |
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| • Misaligned burners, | blower if necessary. | See “Vent/Flue |
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| • Check burners for proper | ||
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| blocked flue and/or air | Pipe” section for | |
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| alignment. | ||
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| inlet pipe, or failed | piping details. | |
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| • Check flue and air inlet | ||
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| induced draft blower. | • Replace pressure | |
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| piping for blockage, | ||
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| • Loose or improperly | switch with proper | |
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| proper length, elbows, | ||
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| connected wiring. | and termination. Correct | replacement part. |
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| as necessary. |
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| • Check induced draft |
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| blower for proper |
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| performance. Replace, if |
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| necessary. |
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| • Tighten or correct wiring |
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| connection. |
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| • Integrated control module | 5 | • Flame sensed with |
| • Short to ground in flame | • Correct short at flame | • Turn power OFF |
| diagnostic LED is flashing | no call for heat. |
| sense circuit. | sensor or in flame | prior to repair. | |
| FIVE (5) times. |
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| • Lingering burner flame. | sensor wiring. |
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| • Induced draft blower and | 5 FLASHES |
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| • Check for lingering |
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| • Slow closing gas valve |
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| circulator blower run |
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| flame |
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| continuously. No furnace |
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| • Verify proper operation |
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| operation. |
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| of gas valve |
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| • Furnace fails to operate. | C | • Polarity of 115 |
| • Polarity of 115 volt AC | • Review wiring diagram to | • Turn power OFF |
| • Integrated control module | volt power is |
| power to furnace or | correct polarity. | prior to repair. | |
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| diagnostic LED is flashing |
| reversed. |
| integrated control module | • Verify proper ground. |
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| continuously. | CONTINUOUS |
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| is reversed. | Correct if necessary. |
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| FLASHING |
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| • Poor unit ground. | • Check and correct wiring. |
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| • Normal furnace |
| • Flame sense |
| • Flame sensor is coated/ | • Sand flame sensor is | • Turn power OFF |
| operation. | 7 | microamp signal is |
| oxidized. | coated/oxidized. | prior to repair. |
| • Integrated control |
| low. |
| • Flame sensor incorrectly | • Inspect for proper sensor | • Sand flame |
| module diagnostic LED | 7 FLASHES |
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| positioned in burner | alignment. | sensor with |
| is flashing SEVEN (7) |
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| flame. | • Check inlet air piping for | emery clot. | |
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| flashes. |
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| • Lazy burner flame due to | blockage, proper length, | • See “Vent/Flue |
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| improper gas pressure or | elbows, and termination. | Pipe” section for |
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| combustion air. | • Compare current gas | piping details. |
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| pressure to rating plate | • See rating plate |
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| info. Adjust as needed. | for proper gas |
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| pressure. |
| • Furnace not operating. |
| • Problem with |
| • Improperly | • Check and correct wiring | • Turn power OFF |
| • Integrated control module | 8 | igniter circuit. |
| connected igniter | from integrated control | prior to repair. |
| diagnostic LED is flashing |
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| • Bad igniter | module to igniter | • Replace igniter |
| 8 FLASHES |
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| • Replace bad igniter | |||
| EIGHT (8) flashes. |
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| • Poor unit ground | with proper | ||
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| • Check and correct unit | silicon nitride |
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| replacement part. | |
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| ground wiring | |
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| • Furnace operating on |
| • High stage |
| • Pressure switch hose | • Inspect pressure switch | • Turn power OFF |
| low stage gas with high | 9 | pressure switch |
| blocked, pinched or | hose. Repair, if necessary. | prior to repair. |
| stage induced draft blower |
| circuit does not |
| connected improperly. | • Inspect flue and/or inlet | • Replace pressure |
| • High stage circulator | 9 FLASHES | close in response |
| • Blocked flue and/or inlet air | air piping for blockage, | |
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| switch with | |||||
| blower (temperature, of |
| to high stage |
| pipe, blocked drain system, | proper length, elbows, | |
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| proper | ||||
| conditioned air, lower than |
| induced draft |
| or weak induced draft | and termination. Check | |
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| replacement part. | ||||
| typical). |
| blower operation. |
| blower. | drain system. Correct as | |
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| • Integrated control module |
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| • Incorrect pressure switch | necessary. |
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| • Correct pressure switch |
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| setpoint or malfunctioning |
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| diagnostic LED is flashing |
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| switch contacts. | setpoint or contact |
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| NINE (9) flashes. |
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| • Loose or improperly | motion. |
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| • Tighten or correct wiring |
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| connected wiring. |
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| connection. |
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30 | 12/04 |
