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Single or 2:1 Stage Furnace Will Not Light
Troubleshooting
Ignition controller (IC#)
red LED
blinks 7 times or is on
Ignition controller (IC1) failed.
(Replace ignition controller)
High limit (HLC1) open?
Discharge temperature was above high limit setting.
Wait for high limit to cool and reset.
24 VAC across A and 21?
Discharge air selector (TS2) improperly set or faulty
Adjust setting (see Staged Start-Up) or replace sensor
Furnace stage one contact (SC1) defective (stage only)
Replace furnace stage one contact
24 VAC across 22 and 21?
Heating Transformer (TR2) Fault
Replace heating transformer
Yes
No
No
Yes
No
Yes
Yes
24 VAC across W1 and X?
Heat Switch (S4) open
(Turn Heat Switch (S4) on)
No
Yes
24 VAC across R and X?
Main disconnect (DS1) open or defective
Close, repair or replace
Main transformer (TR1) fault
Replace main transformer
No
Yes
Ignition controller (IC#)
red LED
blinks 6 times
Combustion blower (CM) not functioning
Replace combustion blower or relay (CR)
Air proving switch (PS2) defective.
Replace air proving switch
Yes
No
Ignition controller (IC#)
red LED blinks
1 time, 2 times or 4 times
Improper manifold pressure
Set high and low manifold pressure (refer to Single Stage or
2:1 Staged Control Start-Up section)
Faulty spark rod or spark gap does not equal 1/8 inch
Replace spark rod or adjust gap to
1
⁄8 inch
Yes
No
Everything is working
properly, consult factory.
Yes
24 VAC across 24 VAC and
21 on SC1 controller?
Optional inlet air sensor (TS4) open
Adjust setting. Reference Blower Start-Up, Step #6
Heat relay (RH) is not energized
Check for loose connections. Repair or replace heat relay (RH)
No
Yes
®
Model IG / IGX Make-Up Air