Troubleshooting

4:1 Modulating 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

N.O. contact on

heat relay (RH) closed?

Yes

DT1 displayed

on furnace controller (SC1)?

No

OT1 displayed

on furnace controller (SC1)?

No

Blank screen

on furnace controller (SC1)?

No

24 VAC across

terminals S and T?

Yes

Continues on next page...

No

No

No

No

Yes

Yes

Yes

No

Main disconnect (DS1) open or defective

Close, repair or replace

Main transformer (TR1) fault

Replace main transformer

Heat switch (S4) open or not wired

Close or replace heat switch (S4)

Heat transformer (TR2) fault

Replace heating transformer

Heat relay (RH) is not energized

Check for loose connections. Repair or replace heat relay (RH)

Discharge air sensor (TS2) not wired or defective

Wire or replace discharge air sensor (TS2)

Outdoor air sensor (TS1) not wired or defective

Wire or replace outdoor temperature sensor (TS1)

Furnace controller (SC1) defective or not powered

Replace or wire furnace controller (SC1)

Discharge temperature was above high limit control (HLC1)

Wait for high limit to cool and reset

Inlet air sensor contact open

Adjust inlet air sensor setting (refer to 4:1 Modulation Start-Up section)

Furnace controller (SC1) defective

Replace furnace controller (SC1)

52 Model IG / IGX Make-Up Air

®

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Image 52
Greenheck Fan 470656 manual Heat transformer TR2 fault