Greenheck Fan 470656 manual Single or 21 Stage Furnace Will Not Light, Improper manifold pressure

Troubleshooting

Single or 2:1 Stage Furnace Will Not Light

24 VAC across R and X?

Yes

24 VAC across W1 and X?

Yes

24 VAC across 22 and 21?

Yes

24 VAC across 24 VAC and

21 on SC1 controller?

Yes

24 VAC across A and 21?

Yes

High limit (HLC1) open?

No

Ignition controller (IC#) red LED

blinks 7 times or is on

No

Ignition controller (IC#) red LED

blinks 6 times

No

Ignition controller (IC#) red LED blinks

1 time, 2 times or 4 times

Yes

Everything is working

properly, consult factory.

No

No

No

No

No

Yes

Yes

Yes

Yes

Main disconnect (DS1) open or defective

Close, repair or replace

Main transformer (TR1) fault

Replace main transformer

Heat Switch (S4) open

(Turn Heat Switch (S4) on)

Heating Transformer (TR2) Fault

Replace heating transformer

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)

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

Discharge temperature was above high limit setting.

Wait for high limit to cool and reset.

Ignition controller (IC1) failed.

(Replace ignition controller)

Combustion blower (CM) not functioning

Replace combustion blower or relay (CR)

Air proving switch (PS2) defective.

Replace air proving switch

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

50 Model IG / IGX Make-Up Air

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