Unit Fails To Fire In The Heating Mode, Combustion Air Inducer Energizes, Ignitor Is Not Energized - Lennox G61MPV Service Manual

PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER DOES
Condition
2.3
− Unit operates with a cooling and con-
tinuous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Diagnostic lights flash the pressure
switch failure code 2.5 minutes after switch failure code 2.5 minutes after
heating demand.
LED#1−Off,
LED#2−Slow Flash
PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER
Condition
3.1
− Unit operates with a cooling and
continuous fan demand.
− Combustion air inducer energizes
with a heating demand with a heating demand.
− Diagnostic lights flash the pressure
switch failure code 2.5 minutes after
heating demand. g
LED#1−Off LED#1 Off
LED#2−Slow Flash
NOT ENERGIZE (CONT.).
Possible Cause
2.3.1
Miswiring of furnace or improper
connections to combustion air induc-
er.
2.3.2
Combustion air inducer failure.
ENERGIZES, IGNITOR IS NOT ENERGIZED.
Possible Cause
3.1.1
Prove switch does not close due to
incorrect routing of the pressure
switch lines.
3.1.2
Prove switch does not close due to
obstructions in the pressure lines.
3.1.3
Prove switch lines damaged
3.1.4
Condensate in prove switch line.
3.1.5
Prove switch does not close due to a
low differential pressure across the
prove switch.
3.1.6
Wrong prove switch installed in the
unit, or prove switch is out of
calibration.
3.1.7
Miswiring of furnace or improper
connections at prove switch.
3.1.8
Prove switch failure.
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Corrective Action/Comments
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
ACTION 1 − If there is 120V to combustion air in-
ducer and it does not operate, replace combus-
tion air inducer.
Corrective Action/Comments
ACTION 1 − Check that the prove switch lines are
correctly routed. Correctly route pressure switch
lines.
ACTION 1 − Remove any obstructions from the
the pressure lines and/or taps.
ACTION 1 − Check prove switch lines for leaks.
Replace any broken lines.
ACTION 1 − Check prove switch lines for conden-
sate. Remove condensate from lines.
ACTION 1 − Check the differential pressure
across the prove switch. This pressure should
exceed the set point listed on the switch.
ACTION 2 − Check for restricted inlet vent. Re-
move all blockage.
ACTION 3 − Check for proper vent sizing and
run length.
ACTION 1 − Check that the proper prove switch
is installed in the unit. Replace prove switch if
necessary.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
ACTION 1 − If all the above modes of failure have
been checked, the prove switch may have failed.
Replace prove switch and determine if unit will
operate.