Status Code 34 - Ignition-Proving Fault - Bryant 355CAV A Series Troubleshooting Manual

Status Code 34
IGNITION-PROVING FAULT - This status code indicates flame was not sensed during trial for ignition period. The control will
repeat ignition sequence 3 more times before going to status code 14 - IGNITION LOCKOUT. This status code can also
indicate flame signal was lost during steady-state operation.
STEP
1. Shut the power off, remove the blower access panel, and disconnect User Interface ABCD
connector (if used) or the R thermostat lead (if used) from the furnace control board.
2. Turn the power on and depress the door switch. Use a piece of tape to hold it closed.
3. Jumper the R and W/W1 thermostat terminals.
4. Observe the operation of the furnace through a heating cycle.
5. Does status code 34 flash?
6. Does a different status code flash?
7. Go to page number indicated in the Index for the section covering the status code.
8. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
9. Turn off the power and disconnect the jumper across the R and W/W1 thermostat terminals.
10. Turn the power on.
11. Check the hot surface igniter. To do this run a COMPONENT TEST by putting setup switch
SW1-6 in the ON position. Does the igniter glow orange/white hot by the end of the 15 second
warm-up period?
12. Hook an AC voltmeter across PL2-3 and L2 on the variable speed furnace control. Repeat the
COMPONENT TEST by turning setup switch SW1-6 OFF and then back ON. Is 115-vac
across PL2-3 and L2 during the 15 second warm-up period?
13. Replace the variable speed furnace control.
14. Check continuity in harness and igniter. Replace failed component.
15. Fix problem.
16. Put setup switch SW1-6 in the OFF position, jumper the R and W/W1 thermostat terminals,
and monitor voltage across BLUE and GREEN/YELLOW wires to gas valve GV.
17. Just before status code 34 begins flashing was 24-vac across BLUE and GREEN/YELLOW
wire to gas valve GV?
18. Turn off the power.
19. Do you have continuity across the following connections?
- PL1-10 and the BLUE wire at the gas valve GV.
- PL1-5 and the GREEN/YELLOW wire at the gas valve GV.
20. The BLUE or GREEN/YELLOW wire from the variable speed furnace control to the gas
valve GV is not making a good connection. Repair the wire(s) or replace the harness.
21. Does the gas valve open and allow gas to flow?
22. Are all the manual gas cocks and the gas valve switch in the ON position?
23. Replace gas valve.
24. Do the main burners ignite?
25. Check for the following:
- Inadequate flame carryover or rough ignition.
- Low inlet gas pressure.
- Air leakage between cell panel and burner box assembly.
- Air leakage between combustion air intake box and burner box housing.
- Proper firing rate.
26. Do the main burners stay on longer than a few seconds?
27. Turn off the power and disconnect the jumpers across the R, W/W1, and W2 thermostat
terminals.
28. Connect a DC microampmeter in series with the flame sensor wire.
29. Turn power on and jumper R, W/W1, and W2 thermostat terminals.
30. Is the DC current below .5 microamps?
31. Check connections and retry. If current is near typical value (4.0 to 6.0 microamps) and main
burners will not stay on longer than a few seconds, check the following:
- Air leakage between cell panel and burner box assembly.
- Air leakage between combustion air intake box and burner box housing.
- Inadequate flame carryover on rough ignition.
- Low inlet gas pressure.
- Low manifold pressure. Reference installation instructions for proper manifold pressure.
- Slow opening gas valve. Gas should flow at full pressure within 4 seconds after the gas
valve is energized.
If the above items are OK replace the variable speed furnace control.
ACTION
- 28 -
YES NO GO TO
2
3
4
5
9 6
7 8
INDEX
INDEX
10
11
16 12
14 13
8
15
8
17
21 18
19
13 20
8
24 22
23 15
8
26 52
15
36 52
28
29
30
32 31
15