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SERVICING
S-311 HIGH ALTITUDE APPLICATION (USA)
A high altitude kit is required for installationsabove 7,000 ft.
Refer to the accessory matrix in this manual to determine
the proper natural gas and LP gas high altitude kit for your
furnace.
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 locat-
ing 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 CON-
TROL 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 AVOID THE RISK OF ELECTRICAL SHOCK, WIRING TO THE UNIT
MUST BE PROPERLY POLARIZED AND GROUNDED.
BEFORE PERFORMING SERVICE LISTED BELOW.
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 electro-
mechanical device and is not field repairable. Complete unit
must be replaced.
L
INE VOLTAGE NOW PRESENT
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.
WARNING
D
ISCONNECT POWER
WARNING
L
INE VOLTAGE NOW PRESENT
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 mea-
suring 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.
S-314 CHECKING FLAME SENSOR
A flame sensing device is used in conjunction with the ignition
control module to prove combustion. If proof of flame is not
present the control will de-energize the gas valve and "retry"
for ignition or lockout.
HIGH VOLTAGE
D
ALL
ISCONNECT
POWER BEFORE SERVICING OR
M
INSTALLING THIS UNIT.
ULTIPLE POWER SOURCES MAY
F
BE PRESENT.
AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
1. Connect a micro-amp meter in series with this wire and
the sensor terminal.
2. Be sure the positive side of the meter is to the sensor
(depending on the model) and the negative side of the
meter is to sensor terminal.
L
INE VOLTAGE NOW PRESENT
3. Place the unit into a heating cycle.
4. As soon as flame is established a micro-amp reading
should be evident once proof of flame (micro-amp read-
ing) is established, the hot surface ignitor will be de-en-
ergized.
5. The Integrated Ignition controls will have 1 to 4 mi-
cro-amps. If the micro-amp reading is less than the
minimum specified, check for high resistance wiring
WARNING
WARNING
WARNING
53
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