TROUBLESHOOTING
DIAGNOSTIC TABLE
DS 1 (Red) | DS 2 (Green) | Error/Condition | Comments/Troubleshooting |
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Simultaneous | Simultaneous | Normal operation | No fault |
slow flash | slow flash |
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Simultaneous | Simultaneous | Normal operation with | Normal operation |
fast flash | fast flash | call for heat |
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Slow flash | On | Open limit switch | Verify continuity through rollout switch circuit |
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Off | Slow flash | Pressure switch stuck | Pressure switch stuck closed. Check switch function, verify |
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| closed/open | inducer is turning off. |
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| Pressure switch stuck open. Check pressure switch function |
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| and tubing. Verify inducer is turning on and pulling sufficient |
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| vacuum to engage switch. |
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Alternate | Alternate slow | External lockout | Failure to sense flame is often caused by carbon deposits on |
slow flash | flash | (retries) | the flame sensor, a disconnected or shorted flame sensor |
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| lead or a poorly grounded furnace. Carbon deposits can be |
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| cleaned with emery cloth. Verify sensor is not contacting the |
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| burner and is located in a good position to sense flame. |
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| Ignitor must be positioned to light the gas immediately when |
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| the valve opens. If the ignitor has been replaced, verify hot |
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| spot position has not changed. |
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| Check sensor lead for shorting and verify furnace is |
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| grounded properly. |
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Slow flash | Off | Flame sensed with gas | Verify the gas is operating and shutting down properly. Flame |
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| valve | in burner assembly should extinguish promptly at the end of |
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| the cycle. Check orifices and gas pressure. |
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On | Slow flash | Open rollout switch | Verify continuity through rollout switch circuit. |
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On | On | Module – internal fault | Module contacts for gas valve not operating or processor |
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| condition | fault. Reset control, if condition persists, replace module. |
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Slow flash | Fast flash | Low flame sense | Low flame sense current is often caused by carbon deposits |
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| current | on the flame sensor, a poorly grounded furnace or a mis- |
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| aligned flame sense probe. Carbon deposits can be cleaned |
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| with emery cloth. |
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| Check or improve furnace and module ground. Verify sensor |
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| is located in or very near flame as specified by the appliance |
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| manufacturer. |
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Fast flash | Slow flash | Grounding or | Verify the control and furnace are properly grounded. Check |
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| reversed polarity | and reverse polarity (primary) if incorrect. |
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Alternate fast | Alternate fast | Module ignitor | Fault code indicates the module ignitor contacts are not |
flash | flash | contact failure | functioning properly. Replace module. |
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Homeowner Help Line: 1-800-284-2925
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