Fault Code 34
IGNITION PROVING FAULTÐThis fault can indicate 1 of the following:
·Flame was not sensed during trial for ignition period. The control will repeat ignition sequence 3 more times before going into Fault
14ÐIGNITION LOCKOUT.
·The flame signal was lost after trial for ignition period.
·The flame signal was sensed while gas valve was
STEP |
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1. | Turn power off, remove blower access panel, and disconnect R thermostat lead from furnace con- | Ð | Ð | 2 | ||
trol board. | ||||||
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2. | Turn power on and depress door switch. Use a piece of tape to hold switch closed. | Ð | Ð | 3 | ||
3. | Make sure thermostat is NOT calling for heat and reconnect R thermostat lead to furnace control |
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board. Observe unit for 15 minutes. Does inducer motor ever turn on at full speed while furnace | 4 | 5 | Ð | |||
| control board flashes Fault Code 34? |
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4. | Replace furnace control board. Make sure it has a date code 9405 or later. | Ð | Ð | 12 | ||
5. | Disconnect R thermostat lead from furnace control board and jumper R and W/W1 thermostat termi- | Ð | Ð | 6 | ||
nals on furnace control board. | ||||||
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6. | Observe operation of furnace through 1 heating cycle. | Ð | Ð | 7 | ||
7. | Does fault occur again? | 13 | 8 | Ð | ||
8. | Does a different fault occur? | 9 | 10 | Ð | ||
9. | Go to page number indicated in Index for fault code flashed. | Ð | Ð | INDEX | ||
10. | Disconnect jumper wire across R and W/W1 thermostat terminals. Does fault occur now? | 11 | 12 | Ð | ||
11. | Replace gas valve. | Ð | Ð | 12 | ||
12. | Go to page number indicated in Index for CLEANUP AND | Ð | Ð | INDEX | ||
13. | Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. | Ð | Ð | 14 | ||
14. | Turn power on and wait several sec before proceeding to next step. | Ð | Ð | 15 | ||
15. | Check hot surface ignitor. To do this, put setup switch | 20 | 16 | Ð | ||
tion. Does ignitor glow orange/white hot by end of | ||||||
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16. | Disconnect PL4 from furnace control board. Connect an AC voltmeter across |
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furnace control board. Repeat COMPONENT TEST by turning setup switch | 18 | 17 | Ð | |||
| back ON. Do you see 120 vac across |
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17. | Replace furnace control board. | Ð | Ð | 12 | ||
18. | Check continuity in harness and ignitor. Replace defective component. | Ð | Ð | 19 | ||
19. | Fix problem. | Ð | Ð | 8 | ||
20. | Put setup switch | Ð | Ð | 21 | ||
21. | Jumper R and W/W1 thermostat terminals on furnace control board. | Ð | Ð | 22 | ||
22. | Connect an AC voltmeter across BLUE and GREEN wires to gas valve GV. Does gas valve GV re- | 26 | 23 | Ð | ||
ceive 24v? | ||||||
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23. | Turn power off. | Ð | Ð | 24 | ||
24. | Do you have continuity across the following connections: |
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25. | The BLUE or GREEN wire from furnace control board to gas valve GV is not making good connec- | Ð | Ð | 12 | ||
tion. Repair wire(s) or replace harness. | ||||||
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26. | Does gas valve open and allow gas to flow? | 28 | 27 | Ð | ||
27. | Are all manual gas cocks in ON position? | 11 | 19 | Ð | ||
28. | Do main burners ignite? | 30 | 29 | Ð | ||
29. | Check for the following: |
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· | Inadequate flame carryover or rough ignition. | Ð | Ð | 19 | ||
| · | Low inlet gas pressure. |
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30. | Do main burners stay on? | 40 | 31 | Ð | ||
31. | Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. | Ð | Ð | 32 | ||
32. | Connect a DC microammeter in series with flame sensor wire. | Ð | Ð | 33 | ||
33. | Turn power on and wait several sec then jumper R and W/W1 thermostat terminals on furnace con- | Ð | Ð | 34 | ||
trol board. | ||||||
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34. | Is DC current below 0.5 microamps? | 36 | 35 | Ð | ||
35. | Check connections and recheck current. If current is near typical value and control will not stay on, | Ð | Ð | 12 | ||
replace furnace control board. | ||||||
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36. | Clean flame sensor with fine sandpaper and recheck current. Current is typically 4.0 to 6.0 micro- | Ð | Ð | 37 | ||
amps. | ||||||
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37. | Is current near typical value? | 39 | 38 | Ð | ||
38. | Replace electrode. | Ð | Ð | 12 | ||
39. | Will main burners ignite and stay on? | 12 | 17 | Ð | ||
40. | Do you have combustion pulsations? | 41 | 47 | Ð |
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