Lennox G60UH - Troubleshooting Combustion Air Inducer and Pressure Switch Issues

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PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES NOT
ENERGIZE
Condition Possible Cause Corrective Action / Comments
2.1
− Unit operates with a cooling or contin-
uous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Diagnostic lights flash the limit failure
mode
2.1.1
Primary Limit or secondary limit (if
equipped ) or rollout switch open.
ACTION 1 − Check continuity across switch(es).
Switches reset automatically upon cool down.
Rollout switch must be reset manually.
ACTION 2 − Check for restrictions on blower inlet
air (including filter) and outlet air. Determine
cause for limit activation before placing unit back
in operation.
mo
d
e.
LED#1−Slow Flash,
LED#2−On
2.1.2
Miswiring of furnace or improper con-
nections at limit switch(es).
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
2.2
− Unit operates with a cooling and con-
tinuous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Dia
g
nostic li
g
hts flash the
p
ressure
2.2.1
Miswiring of furnace or improper con-
nections to combustion air inducer.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
−
Diagnostic
lights
flash
the
pressure
switch failure code.
LED#1−Off,
LED#2−Slow Flash
2.2.2
Pressure switch stuck closed.
ACTION 1 − Check that the pressure switch is
open without the combustion air inducer operat-
ing. Replace if defective.
PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER DOES
NOT ENERGIZE
Condition Possible Cause Corrective Action/Comments
3.3
− 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
3.3.1
Miswiring of furnace or improper con-
nections to combustion air inducer.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
switch failure code 2.5 minutes after
heating demand.
LED#1−Off,
LED#2−Slow Flash
3.3.2
Combustion air inducer failure.
ACTION 1 − If there is 120V to combustion air in-
ducer and it does not operate, replace combus-
tion air inducer.