Greenheck PVF Installation And Operation Manual page 27

Troubleshooting
8 Stage Furnace Will Not Light
In all cases, verify correct terminals as shown on the unit-specific wiring diagram.
... continued from
previous page.
With the combustion blower
(CM) on for at least
30 seconds, is there
24 VAC across T and A or E?
Yes
Ignition controller (IC#)
red LED blinks
7 times or is on
No
Ignition controller (IC#)
red LED blinks
1 time, 2 times or 4 times
No
Cycle power to the unit
and wait 30 seconds
Does the combustion relay
(R9 or CR) close?
Yes
Does the combustion
blower (CM) run?
Yes
Does the combustion
blower stop after
30 seconds of operation?
No
Everything is working properly,
consult factory.
®
No
Furnace controller (SC1) defective
Yes
Yes
Faulty spark rod or spark gap does not equal 1/8 inch
Replace spark rod or adjust gap to 1/8 inch
No
Internal high limit tripped (temperature above set point)
(refer to Reference - FX Controller, Access the Inlet Air Sensor section)
Combustion relay (R9 or CR) defective
Replace defective combustion relay (R9 or CR)
No
Combustion blower fuse (FU9) blown
Combustion blower (CM) defective
Replace defective combustion blower (CM)
Yes
Replace furnace controller (SC1)
Ignition controller(s) (IC#) failed
Replace faulty ignition controller(s)
Improper manifold pressure
Set high and low manifold pressure
(refer to 8 Staged Start-Up section)
Let temperatures cool
Internal inlet air sensor open
Adjust inlet air sensor setting
Replace combustion blower fuse (FU9)
Airflow switch (PS2) defective
Replace defective airflow switch (PS2)
Airflow relay (R9) defective
Replace defective airflow relay (R9)
Indirect Gas-Fired Heat Modules 27