Greenheck IG / IGX (464104 IOM) (Pre-2009) - Manual (Page 71)

71
8:1 Staged Furnace Will Not Light
Troubleshooting
Internal control failure?
(ignition controller(s) LED on)
Ignition controller(s) (IC#) failed
Replace faulty ignition controller(s)
Yes
... continued from previous
page.
Does the combustion relay
(IR# or CR#) close?
Internal high limit tripped (temperature above set point)
Let temperatures cool
Internal inlet air sensor open
Adjust inlet air sensor setting (refer to 8:1 staged start-up)
Combustion relay (IR# or CR#) defective
Replace defective combustion relay (IR# or CR#)
No
Yes
Does the combustion blower
(CM#) run?
Combustion blower fuse (FU9) blown
Replace combustion blower fuse (FU9)
Combustion blower (CM#) defective
Replace defective combustion blower (CM#)
No
Yes
No
Ignition lockout?
(ignition controller LED
blinking three times)
No
Cycle power to the unit and
wait 30 seconds
Everything is working
properly, consult factory.
Improper manifold pressure
Set high and low manifold pressure (refer to 8:1 staged start-up)
Faulty spark rod or spark gap does not equal 1 ⁄
8
in.
Replace spark rod or adjust gap to 1 ⁄
8
in.
Yes
Does the combustion blower
stop after 30 seconds of
operation?
Airflow switch (PSH#) defective
Replace defective airflow switch
Airflow relay (PSR) defective
Replace defective airflow relay (PSR)
Yes
No
With the combustion blower
(CM#) on for at least 30
seconds, is there 24 VAC
across X and A1 or A2?
Furnace controller (FX) defective
Replace furnace controller (FX)
No
Yes
Troubleshooting