Instruction manual
35
■ 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