Heater System Solving Guide
FAULT CODE THUMBNAILS – PAGE F 10
FAULT CODE THUMBNAILS – PAGE F 10
Heater System Solving Guide
Fault Code Thumbnails IF Ignition Failure
FAULT CODE THUMBNAILS IF IGNITION FAILURE (INSUFFICIENT FUEL)
IF
IGNITION FAILURE
(INSUFFICIENT FUEL)
UHS, IDL2, IDL, ED2
REQUIRED DIAGNOSTIC TOOLS
• Manometer
• Multimeter
PARTS THAT MAY BE NEEDED
• Flame Sensor
• Ignitor
• Ignition Board / Control Module
• Gas Valve
While IF actually stands for Ignition Failure, this code is often
referred to as the Insufficient Fuel code – since the most common
reason for an “IF” code is inadequate gas supply to the heater.
—————
“IF” occurs when the heater passes all safety checks but the heater fails to
ignite.
Without the proper gas/air mixture, the heater will not light. Since the
heater has gone through most of the steps within the Sequence of Op-
eration, the problem is most likely gas supply or a faulty ignition board,
flame sensor, ignitor or gas valve.
Investigate and ensure that the gas train is correct.
The source of an IF code is found in the gas train 90% of the time.
DIAGNOSTIC SEQUENCE
A. Ensure that main gas shutoff adjacent to heater is open. Ensure that
knob on gas valve inside unit is in ‘‘on’’ position. If OK, proceed to
next step.
B. Check for low gas supply pressure by ensuring inlet gas supply pres-
sure is between the minimum and maximum values indicated on rating
plate. If OK, proceed to next step.
C. Inspect flame sense wiring, and ensure wire harness terminals are se-
curely fastened to flame sense and to control module. If OK, proceed
to next step.
D. Inspect gas valve wiring, and ensure wire harness terminals are se-
curely fastened to spade terminals on gas valve. If OK, proceed to next
step.
E. Check for gas valve failure or gas valve relay failure.1. Measure volt-
age across gas valve during trial for igintion.
I. If 24VAC is present and gas valve does not open, gas valve is de-
fective and must be replaced.2.
II. If 24VAC is not present, gas valve relay on control module is defec-
tive, which means the control module must be replaced.
F. Inspect gas orifices for blockages that could prevent gas flow. Also re-
move and inspect burners for blockages.
To Next Page
Loading...
