SYSTEM OPERATION
40
Chart - ComfortNet™
have been verified.
2.
System Lockout.
If a flame is not sensed during the
first seven (4) seconds after the gas valve is energized,
the control turns off the gas. There will then be a 30
second delay while the induced draft blower is ener-
gized to purge the heat exchanger. The ignitor will again
be energized and preheated for an additional (1) sec-
ond. The gas valve will then be energized. If flame is not
sensed the gas valve will be de-energized and another
purge will occur and a third ignitor warm up for an addi-
tional (2) seconds will occur. The control will cycle the
gas valve a total of three (3) times before it determines
it cannot establish measurable combustion and enters
a locked out state. The diagnostic error code for this
problem is
E0
. The control can be reset and brought out
of lockout mode by turning the thermostat off for more
than (5) seconds and less then (20) seconds and then
back on. It can also be reset by turning off the electrical
disconnect switch to the furnace for a minimum of 5
seconds.
NOTE:
The control board will automatically reset one hour
after lockout occurs. If the furnace frequently has to be re-
set, it means that a problem exists that should be cor-
rected. Refer to
Troubleshooting Chart - ComfortNet™
on
the following pages for aid in determining the cause.
3.
Low Stage Pressure Switch Stuck Closed.
If the con-
trol senses the low stage pressure switch is closed
when the induced draft blower is off, it waits until the
fault is corrected. The diagnostic error code for this prob-
lem is
E1
. The probable cause is either a faulty pres-
sure switch or wiring.
4.
Low Stage Pressure Switch Stuck Open.
If, after
the induced draft blower is energized, the low stage
pressure switch does not close within 5 minutes, the
control will go into a 1-hour lockout. The control will
automatically reset fro lockout and restart the ignition
sequance. The diagnostic error code for this problem is
E2
. The probable causes are either disconnected hose
to the pressure switch, faulty pressure switch or wiring,
restricted air intake or flue piping.
5.
Open Primary, Auxiliary, or Rollout Limit.
If the limit
control opens, the air circulator blower and induced draft
blower will be turned on until the limit closes. The diag-
nostic error code for this problem is
E3
. The probable
cause is either low conditioned air flow due to dirty filter
or resistance in duct work, faulty limit, faulty blower,
blower speed set to low, misaligned burners, faulty in-
duced draft blower, or blocked flue.
6.
Flame Sensed with No Call for Heat.
If the control
senses a flame when the gas valve is de-energized, it
will run the air circulation blower and the induced draft
blower continuously with no further furnace operation.
The diagnostic error code for this condition is
E4
. The
probable causes are either a short to ground in flame
sense circuit, miswiring, lingering burner flame or a slow
closing gas valve.
7.
Open Fuse.
If the control detects an open fuse, it will
inhibit all furnace operation, except the display of the
error code. The diagnostic error code for this condition
is
E5
. The probable cause is a short in the low voltage
wiring, either internal to the furnace or external to the
furnace.
8.
Low Flame Sense Signal.
If the furnace continues to
operate and the micro-amp signal from the flame sen-
sor falls below specified level. The diagnostic error code
for this problem is
E6
. The probable cause is either a
coated/oxidized sensor, incorrectly positioned senser
in burner flame or lazy burner flame due to improper
gas pressure or combustion air.
9.
Check Igniter or No Ground Condition.
Check for
broken or improperly connected igniter. Check for proper
ground and correct. The diagnostic error code for this
problem is
E7
.
10.
High Stage Pressure Switch Stuck Closed.
If the
control fails to operate at high stage heat when com-
manded to do so, the high stage pressure switch is
stuck closed. For this condition, the furnace will oper-
ate at low stage only, regardless of the thermostat de-
mand. The diagnostic error code for this condition is
E8
. The probable cause is sticking high stage pres-
sure switch contacts or a short in the high stage pres-
sure switch wiring.
11.
High Stage Pressure Switch Stuck Open.
This con-
dition can occur if the pressure switch hose is blocked
or pinched. Check for blocked flue and/or inlet air pipe.
Blocked drain, weak induced draft blower and malfunc-
tioning pressure switch are possible. The diagnostic
error code for this problem is
E9
followed by a pause.
12.
Reversed Polarity.
If the 115V or 24V AC power leads
are reversed, the furnace will fail to operate. The diag-
nostic error code for this problem is
EA
. The probable
cause is either the 115V AC power to furnace or inte-
grated control module is reversed, the 24V AC wires to
transformer are reversed, or poor unit ground.
13.
No Shared Data.
The control does not contain any
shared data. Shared data sets contain all the informa-
tion required to drive the variable speed motor as well
as calculate airflow demands. The furnace cannot func-
tion without the approriate shared data set. The diag-
nostic error code for the this condition is
d0
. A memory
card must be used to populate shared data to the con-
trol. Contact your distributor to obtain the appropriate
memory card for your particular furnace model.
NOTE:
Turn
off
power to the furnace prior to inserting
memory card onto the control. With memory card inserted
onto control, turn power to furnace
on
. Control has ac-
cepted memory card data once control displays
OP
on the
dual, 7-segment display. Memory card may be left on con-
trol or removed and used on another furnace of the same
model. Turn power
off
to furnace prior to removing memory
card.
