Lennox G32V Series Service Literature page 88

PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES NOT
Condition
3.3
− Unit operates with a cooling and con-
tinuous fan demand.
− Combustion air blower 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 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER
Condition
4.1
− Unit operates with a cooling and
continuous fan demand.
− Combustion air blower 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
ENERGIZE (CONT.).
Possible Cause
3.3.1
Miswiring of furnace or improper con-
nections to combustion air blower.
3.3.2
Combustion air blower failure.
ENERGIZES, IGNITOR IS NOT ENERGIZED.
Possible Cause
4.1.1
Pressure switch does not close due to
incorrect routing of the pressure
switch tubing.
4.1.2
Pressure switch does not close due to
obstructions in the pressure tubing.
4.1.3
Pressure switch tubing damaged
4.1.4
Condensate in pressure switch tub-
ing.
4.1.5
Pressure switch does not close due to
a low differential pressure across the
pressure switch.
4.1.6
Wrong pressure switch installed in the
unit, or pressure switch is out of cal-
ibration.
4.1.7
Miswiring of furnace or improper con-
nections at pressure switch.
4.1.8
Pressure switch failure.
Page 88
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
blower and it does not operate, replace combus-
tion air blower.
Corrective Action/Comments
ACTION 1 − Check that the pressure switch tub-
ing is correctly routed. Correctly route pressure
switch tubing.
ACTION 1 − Remove any obstructions from the
pressure tubing and/or taps.
ACTION 1 − Check pressure switch tubing for
leaks. Replace any broken tubing.
ACTION 1 − Check pressure switch tubing for
condensate. Remove condensate from tubing.
Check that the condensate tubing is located cor-
rectly.
ACTION 1 − Check the differential pressure
across the pressure switch. This pressure
should exceed the set point listed on the switch.
ACTION 2 − Check for restricted inlet and ex-
haust vent. Remove all blockage.
ACTION 3 − Check for proper vent sizing and
run length. See installation instructions.
ACTION 1 − Check that the proper pressure
switch is installed in the unit. Replace pressure
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 pressure switch may have
failed. Replace pressure switch and determine if
unit will operate.