SERVICING
44
S-312 CHECKING FOR DELAYED IGNITION
Delayed ignition is a delay in lighting a combustible mixture
of gas and air which has accumulated in the combustion
chamber.
Furnace design makes this extremely unlikely unless safety
controls have been by-passed or tampered with. Never by-
pass or alter furnace controls.
If delayed ignition should occur, the following should be
checked:
1. Improper gas pressure - adjust to proper pressure (See
S-307 CHECKING GAS PRESSURE
).
2. Improper burner positioning - burners should be in locating
slots, level front to rear and left to right.
3. Carry over (lighter tube or cross lighter) obstructed - clean.
4. Main burner orifice(s) deformed, or out of alignment to
burner - replace.
S-313 CHECKING INTEGRATED IGNITION
CONTROL BOARDS
NOTE:
Failure to earth ground the furnace, reversing the
neutral and hot wire connection to the line (polarity), or a
high resistance connection in the neutral line may cause the
control to lockout due to failure to sense flame.
T
O
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ID
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E RISK
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RICAL S
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E PR
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NDED
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.
WARNING
The ground wire must run from the furnace all the way back
to the electrical panel. Proper grounding can be confirmed by
disconnecting the electrical power and measuring resistance
between the neutral (white) connection and the burner closest
to the flame sensor. Resistance should be less than 2 ohms.
The ignition control is a combination electronic and
electromechanical device and is not field repairable. Complete
unit must be replaced.
L
INE V
O
L
T
AGE N
O
W PRESEN
T
WARNING
These tests must be completed within a given time frame due
to the operation of the ignition control.
The ignition control is capable of diagnosing many furnace
failures to help in troubleshooting. The trial for ignition period
is 4 seconds.
The indicator light/display may be viewed by looking through
the sight glass in the blower compartment door. If the blower
compartment door is removed, failure to hold the door switch
closed while removing the blower compartment door will
result in the loss of the stored failure code. In most cases
recycling the ignition control will result in the same failure
code originally displayed.
L
INE V
O
L
T
AGE N
O
W PRESEN
T
WARNING
These tests must be completed within a given time frame due
to the operation of the ignition control.
1. Check for 120 volts from Line 1 (Hot) to Line 2 (Neutral)
at the ignition control. No voltage, check the door switch
connections and wire harness for continuity.
2. Check for 24 volts from W to C terminal on the ignition
control. No voltage. Check transformer, room thermostat,
and wiring.
If you have 24 volts coming off the transformer but receive
approximately 13 volts on the terminal board between (C)
and (R), check for blown fuse.
3. Check for 120 volts to the induced draft blower by
measuring voltage between Pin 1 (on the 2-pin connector)
and Line (Neutral) on the control board. No voltage,
replace ignition control.
4. If voltage is present in Steps 1 through 3 and the induced
draft blower is operating, check for 120 volts to the ignitor
during the preheat cycle. Measure voltage between Pin 2
(on the 2-pin connector) and Line (Neutral) on the control
board. No voltage, check pressure switch.
5. After the ignitor warm-up time, begin checking for 24 volts
to the gas valve. Voltage will be present for seven seconds
only if proof of flame has been established.
Red LED Flash
Error / Condition
1
System Lockout (Retries Exceeded)
2
Pressure Switch stuck Closed
3
Pressure Switch stuck Open
4
Open High Temperature Limit Switch
5
Flame Sensed>4.25 Seconds with Gas Valve De-Energized
6
Open High Temperature Limit Switch
8
Igniter Relay Fault
10
Open Fuse
11
Igniter Open
12
Inducer Relay Error
7
Low Flame Sense Signal
9
Twinning Fault
OFF
Control Failure / No Power / Internal Fault / IRQ Loss. Gas Heating
Lockout (Gas valve energized when it should be de-energized) Or Gas
Valve De-energized when it should be Energized
Rapid Flash
Reverse Polarity
ERROR CODE
Flash Codes stored in memory (auto-erased after 14 days)
Flash Codes NOT stored in memory
