Page 103
PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER
ENERGIZES, IGNITOR IS NOT ENERGIZED.
Flash Code
LED X + Y
Possible Cause Corrective Action/Comments
4.1
− Unit operates with a cooling and
continuous fan demand.
− Combustion air inducer energizes
with a heating demand.
− Diagnostic lights flash the pressure
switch failure code 2.5 minutes after
heating demand.
LED 2 + 3
4.1.1
Prove switch does not close due to
obstruction in vent pipe.
ACTION 1 − Check for restricted vent. Remove all
blockage.
ACTION 2: Check for proper vent sizing. See
installation instructions.
4.1.2
Prove switch does not close due to
incorrect routing of the prove switch
line.
ACTION 1 − Check that the prove switch line is
correctly routed. Correctly route prove switch
line.
4.1.3
Prove switch does not close due to
obstructions in the prove switch line.
ACTION 1 − Remove any obstructions from the
the prove switch line and/or taps.
4.1.4
Prove switch line damaged
ACTION 1 − Check prove switch line for leaks.
Replace broken line if required.
4.1.5
Condensate in prove switch line.
ACTION 1 − Check prove switch line for conden-
sate. Remove condensate from line.
4.1.6
Prove switch does not close due to a
low differential pressure across the
prove switch.
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. See installation instructions.
4.1.7
Wrong prove switch installed in the
unit, or prove switch is out of calibra-
tion.
ACTION 1 − Check that the correct prove switch
is installed in the unit. Replace prove switch if
necessary.
4.1.8
Miswiring of furnace or improper con-
nections at prove switch.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
4.1.9
Prove switch failure.
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.
To Next Page
Loading...
