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58SU0A (Series 2 & 3): Troubleshooting Guide
STEP
Observe the furnace operation for at least 20 minutes or until status code starts flashing, monitoring
40.
for any sudden changes in inducer speed, pressure or in voltage
41.
Did status code 31 flash?
42.
Does a different status code flash?
43.
Turn power off and disconnect jumper wire across R and W thermostat terminals.
44.
Was there a drop in transducer voltage to nearly 0 VDC before the code 31 started to flash
45.
Was there a sudden drop in pressure before the code 31 started to flash?
46.
Problem is most likely caused by excessive winds or improperly sized vent system
47.
Was there a sudden drop of inducer speed noticed before the code 31 started to flash
Inspect harness between inducer assembly and furnace control. If no defect is found, replace inducer
48.
assembly
Status Code 34 - Ignition-Proving Failure
Indicates the furnace failed to ignite gas and/or prove presence of flame. Furnace will attempt to light 3 additional times before locking out and indicating status
code 14.
STEP
Shut the power off, remove the blower access panel and disconnect the R thermostat lead from the
1.
furnace control
Assure that all manual gas shut offs are open, and that the switch on the gas valve is in the ON
2.
position
3.
Turn the power on and depress the door switch. Use a piece of tape to hold it closed.
4.
Jumper the R and W thermostat terminals.
5.
Observe the operation of the furnace for 5 minutes.
6.
Does status code 34 flash?
7.
Does a different status code flash?
8.
Run furnace through (2) 10-minute heat cycles
9.
Does status code 34 flash?
10.
Does a different status code flash?
11.
Fix problem.
12.
Go to page number indicated in the Index for the section covering the status code.
13.
Go to page number indicated in Index for CLEANUP AND START- UP INSTRUCTIONS.
Turn off the power and disconnect the jumper across the R and W thermostat terminals. Allow
14.
furnace to cool for 5 minutes
Remove ring terminal with GREEN/YELLOW wire located at gas valve mounting bracket. Check for
15.
corrosion and clean or replace as needed.
16.
Turn power on and jumper R and W thermostat terminals.
17.
Does status code 34 flash?
Check hot surface igniter (HSI) continuity. To do this, unplug igniter connection PL14 and measure
18.
between PL14-1 and PL14-2 on plug half that leads to burner box. Typical igniter resistance should
measure between 40 and 70 Ohms at room temperature
19.
Is measured resistance of Hot surface igniter (HSI) between 40 and 70 Ohms?
20.
Replace hot surface igniter (HSI)
21.
Reattach the Hot surface igniter plug PL14 and turn the power ON.
Check the hot surface igniter (HSI) output. To do this connect an AC voltmeter across terminals
PL14-1 Black (+) and PL14-2 White (-). Run COMPONENT TEST by briefly shorting the
22.
TEST/TWIN terminal to the C terminal at the thermostat terminal strip. Status LED will flash last
status code and then turn ON the inducer motor, followed by the hot surface igniter. Is 115VAC
across PL14-1 and 14-2 during the 15 second igniter period?
Check the hot surface igniter (HSI) output. To do this connect an AC voltmeter across terminals
PL2-1 Black (+) and NEUTRAL L2 White (-) on the furnace control. Run COMPONENT TEST by
23.
briefly shorting the TEST/TWIN terminal to the C terminal at the thermostat terminal strip. Status
LED will flash last status code and then turn ON the inducer motor, followed by the hot surface
igniter. Is 115VAC across PL2-1 and NEUTRAL L2 during the 15 second igniter period?
You have an open wire or bad terminal in either the Black or White igniter wires from the furnace
24.
control to the hot surface igniter (HSI). Repair or replace harness
25.
Replace furnace control
Jumper the R and W thermostat terminals and monitor ac voltage across the BLUE and
26.
GREEN/YELLOW wires to the gas valve GV.
Just before status code 34 begins flashing was 24VAC across the BLUE and GREEN/YELLOW wire
27.
to gas valve GV?
28.
Turn off power and disconnect the jumper across the R and W thermostat terminals.
Connect an AC voltmeter across terminals PL1-10 BLUE (+) and PL1-5 GREEN/YELLOW (-) on the
29.
furnace control
Turn power on and jumper the R and W thermostat terminals and monitor ac voltage across the
30.
PL1-10 BLUE and PL1-5 GREEN/YELLOW wires to the gas valve GV.
Just before status code 34 begins flashing was 24VAC across the BLUE and GREEN/YELLOW
31.
wires at the furnace control?
You have an open wire or bad terminal in either the BLUE or GREEN/YELLOW gas valve wires from
32.
the furnace control to the gas valve. Repair or replace harness
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
ACTION
ACTION
18
YES
NO
GO TO
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43
42
7
8
47
24
45
46
47
9
48
46
9
YES
NO
GO TO
2
3
4
5
6
14
7
12
8
9
14
10
12
13
13
INDEX
INDEX
15
16
17
18
8
19
21
20
11
22
26
23
24
25
11
11
27
33
28
29
30
31
32
25
11
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