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46
■
Furnace fails to
operate on high
stage. Furnace
operates
normally on low
stage.
■
Integrated
control module
LED display
provides “E9”
error code.
E9
■
High-stage
pressure switch
circuit is not
closed.
■
Induced draft
blower is
operating.
■
Furnace is
operating on
low stage only.
■
Pressure switch
hose blocked,
pinched or
connected
improperly.
■
Blocked flue and/or
inlet air pipe,
blocked drain
system or weak
induced draft
blower.
■
Incorrect pressure
switch setpoint or
malfunctioning
switch contacts.
■
Loose or
improperly
connected wiring.
■
Inspect pressure
switch hose. Repair, if
necessary.
■
Inspect flue and/or
inlet air piping for
blockage, proper
length, elbows and
termination. Check
drain system. Correct
as necessary.
■
Check induced draft
blower performance.
Correct as necessary.
■
Correct pressure
switch setpoint or
contact motion.
■
Tighten or correct
wiring connection.
■
Turn off power prior to
repair.
■
Replace pressure
switch with correct
replacement part.
■
Replace induced draft
blower with correct
replacement part.
■
Furnace fails to
operate.
■
Integrated
control module
LED display
provides “EA”
error code.
EA
■
Polarity of 115-
volt AC is
reversed.
■
Polarity of 115-volt
AC power to
furnace or
integrated module
is reversed.
■
Poor furnace
ground.
■
Review wiring diagram
to correct polarity.
■
Verify proper ground.
Correct if necessary.
■
Check and correct
wiring.
■
Turn off power prior to
repair.
■
Furnace fails to
operate.
■
Integrated
control module
LED display
provides “d0”
error code.
d0
■
Data not yet on
network.
■
Furnace does not
contain any shared
data.
■
Populate shared data
set using memory
card.
■
Turn off power prior to
repair.
■
Use memory card for
the specific model.
■
Insert memory card
before turning on
power. Memory card
may be removed after
data is loaded.
■
Turn off power before
removing memory
card.
■
Error code will be
cleared once data is
loaded.
■
Operation
different than
expected or no
operation.
■
Integrated
control module
LED display
provides “d4”
error code.
d4
■
Invalid memory
card data.
■
Shared data set on
memory card has
been rejected by
integrated control
module.
■
Verify shared data set
is correct for the
specific model.
Repopulate data using
correct memory card, if
required.
■
Turn off power prior to
repair.
■
Use memory card for
the specific model.
■
Insert memory card
before turning on
power. Memory card
may be removed after
data is loaded.
■
Turn off power before
removing memory
card.
■
Error code will be
cleared once data is
loaded.
Symptoms of
Abnormal
Operation
Diagnostic/
Status LED
Code
Fault Description Possible Causes
Corrective Actions
Notes and Cautions