Fault code 34 – Carrier 58MVP User Manual
Page 26
Fault Code 34
IGNITION PROVING FAULT—This 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
14—IGNITION LOCKOUT.
•
The flame signal was lost after trial for ignition period.
•
The flame signal was sensed while gas valve was de-energized. The inducer will run at full speed until fault is cleared.
STEP
ACTION
YES
NO
GO TO
1.
Turn power off, remove blower access panel, and disconnect R thermostat lead from furnace con-
trol board.
—
—
2
2.
Turn power on and depress door switch. Use a piece of tape to hold switch closed.
—
—
3
3.
Make sure thermostat is NOT calling for heat and reconnect R thermostat lead to furnace control
board. Observe unit for 15 minutes. Does inducer motor ever turn on at full speed while furnace
control board flashes Fault Code 34?
4
5
—
4.
Replace furnace control board. Make sure it has a date code 9405 or later.
—
—
12
5.
Disconnect R thermostat lead from furnace control board and jumper R and W/W1 thermostat termi-
nals on furnace control board.
—
—
6
6.
Observe operation of furnace through 1 heating cycle.
—
—
7
7.
Does fault occur again?
13
8
—
8.
Does a different fault occur?
9
10
—
9.
Go to page number indicated in Index for fault code flashed.
—
—
INDEX
10.
Disconnect jumper wire across R and W/W1 thermostat terminals. Does fault occur now?
11
12
—
11.
Replace gas valve.
—
—
12
12.
Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
—
—
INDEX
13.
Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals.
—
—
14
14.
Turn power on and wait several sec before proceeding to next step.
—
—
15
15.
Check hot surface ignitor. To do this, put setup switch SW-6 for COMPONENT TEST in ON posi-
tion. Does ignitor glow orange/white hot by end of 15-sec warm-up period?
20
16
—
16.
Disconnect PL4 from furnace control board. Connect an AC voltmeter across PL4-1 and PL4-2 on
furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then
back ON. Do you see 120 vac across PL4-1 and PL4-2 during 15-sec warm-up period?
18
17
—
17.
Replace furnace control board.
—
—
12
18.
Check continuity in harness and ignitor. Replace defective component.
—
—
19
19.
Fix problem.
—
—
8
20.
Put setup switch SW-6 for COMPONENT TEST in OFF position.
—
—
21
21.
Jumper R and W/W1 thermostat terminals on furnace control board.
—
—
22
22.
Connect an AC voltmeter across BLUE and GREEN wires to gas valve GV. Does gas valve GV re-
ceive 24v?
26
23
—
23.
Turn power off.
—
—
24
24.
Do you have continuity across the following connections:
• PL1-2 and BLUE wire at gas valve GV.
• PL1-7 and GREEN wire at gas valve GV.
17
25
—
25.
The BLUE or GREEN wire from furnace control board to gas valve GV is not making good connec-
tion. Repair wire(s) or replace harness.
—
—
12
26.
Does gas valve open and allow gas to flow?
28
27
—
27.
Are all manual gas cocks in ON position?
11
19
—
28.
Do main burners ignite?
30
29
—
29.
Check for the following:
• Inadequate flame carryover or rough ignition.
• Low inlet gas pressure.
—
—
19
30.
Do main burners stay on?
40
31
—
31.
Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals.
—
—
32
32.
Connect a DC microammeter in series with flame sensor wire.
—
—
33
33.
Turn power on and wait several sec then jumper R and W/W1 thermostat terminals on furnace con-
trol board.
—
—
34
34.
Is DC current below 0.5 microamps?
36
35
—
35.
Check connections and recheck current. If current is near typical value and control will not stay on,
replace furnace control board.
—
—
12
36.
Clean flame sensor with fine sandpaper and recheck current. Current is typically 4.0 to 6.0 micro-
amps.
—
—
37
37.
Is current near typical value?
39
38
—
38.
Replace electrode.
—
—
12
39.
Will main burners ignite and stay on?
12
17
—
40.
Do you have combustion pulsations?
41
47
—
26