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Service Procedure I:
80
High Limit (Overheat
Condition)
x
Check the wiring from the sensor to the control module.
x
Measure the resistance of each outside wire to the center wire.
x
If either outside wire has a much different resistance reading, replace
the sensor.
x
Make sure the sensor is securely held inside the well with the clip.
x
If the problem persists and the sensor and wiring check O.K., then
replace the control module.
93
DHW/TEMP
Sensor Fault
x
Check the sensor wire harness from the sensor to the control module.
x
Make sure there are no loose connections to the control plug.
x
Check the resistance reading from each of the outside wires to the
center (common) wire.
x
If the ohm readings are not fairly close, replace the sensor.
x
Replace the control module if the problem persists and the sensor and
wire connections are not defective.
105
Flame detected out of
sequence
x
Check to see if flame is present inside the combustion chamber before
or after the ignition cycle.
x
If so, check to make sure the gas valve is wired correctly.
x
Check for voltage at the gas valve connection.
x
Replace the gas valve if defective.
x
If no flame is visible outside of the ignition sequence/run cycle, then
make sure the flame sensor is wired to the correct terminal.
x
Make sure the ignition cable is not crossing the flame sensor wire or
ignition ground wires.
x
If problem persists and all other checks have been verified, replace the
control module.
110
Ignition Failure
Occurred
x
Burner failed to light or stay lit after 3 retries.
x
Hold condition – will reattempt ignition after 15 minute waiting period.
x
Check gas valve wiring and gas valve operation during the ignition
cycle.
x
If burner lights but quickly goes out, check the flame sensor wire or the
flame sensor.
x
If the flame sensor rod is badly corroded with deposits, clean with
sandpaper or replace.
x
Check the inlet gas supply to make sure the pressure is sufficient and
does not drop after the gas valve opens.
x
Make sure the combustion blower is operating during the ignition and
run cycle.
x
Check the venting system to make sure the inlet and exhaust terminals
and venting system is not blocked.
122
Light-off Rate Proving
Failed
x
If blower speed is not verified from the PWM (Pulse Width Modulation)
signal within 5 minutes, the previously described error code “62”
changes from a hold condition to this lockout code condition.
x
Check the harness and pin terminals for a good connection to the
control module.
x
Replace the control module if the wire harness is good.
137
ILK Open
(Interlock Open)
x
Check if blocked vent safety switch is open.
x
If switch checks O.K., replace control module
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