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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 the R thermostat lead
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 INSTRUC-
TIONS.
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 NEUTRAL- -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 NEUTRAL- -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 and jumper the R and W/W1 thermostat ter-
minals.
17.
Is 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 around igniter bracket.
- - 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 around igniter bracket.
- - 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
24
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
40
15
36
40
28
29
30
32
31
8
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