2.1 Fault Code
Cycle power to furnace.
Connect manometer to
manifold pressure
connector and call for 1
st
stage heat
Does gas ignite?
YES
Is manifold pressure
~3.5"WC (NG)
~10.0"WC (LP)
YES
Do all burners
ignite within 4
seconds?
Check igniter
posi!on and correct
if needed. Check
opera!on
Adjust manifold gas pressure to
~3.5"WC (NG)
~10.0"WC (LP)
Check opera!on
NO
NO
YES
Measure flame
current. Is flame
current less than 0.5
micro-amp?
YES
Possible Causes
Dirty Sensor
Dirty burners
Poor grounding
Sensor loca!on
Wire connec!ons
Flame sensor is good
NO
Disconnect electrical
power to furnace.
Connect manometer
to inlet gas pressure
connector
Is inlet gas pressure above
13.8" WC or less than
nameplate minimum ?
NO
Correct inlet gas pressure.
Maximum pressure is 13.8"WC
Check opera!on
YES
There are two flame sense pads located on the IFC,
marked “FP”. To measure flame current, use a VOM set
to DC volts. Flame current will vary depending on the
type of meter used. Typical flame current ranges from
0.75 – 3.0 micro-amps (0.75 – 3.0 VDC)
Possible causes
Burner alignment
Dirty burners
Low manifold
pressure
Is any gas
pressure
present?
NO
YES
Possible causes
Switch OFF?
No voltage to GV
Debris in gas valve
NO
DEFINITION
RECYCLE Lock Out = 10 recycles within a single
call for heat. Lockout period is for one hour.
Flame is sensed & then lost
All gas appliances in the home should be turned
on to verify gas pressure
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