SYSTEM OPERATION
41
14.
Invalid Memory Card Data.
This condition occurs if
the control rejects the shared data set on a memory
card. Memory cards are model specific. The diagnos-
tic error code for this condition is
d4
.
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.
15.
ECM Blower Motor Not Running.
This condition oc-
curs if the control fails to detect the ECM blower motor
running when it should be running. The furnace will not
operate if the control detects the blower motor is not
running when it should be running. The diagnostic er-
ror code for this condition is
b0
. The probable cause
loose or disconnected wiring between the motor and
control, an open inductor (3/4 Hp and 1 Hp motors only),
or a failed ECM blower motor (see section S-16C in
Servicing
).
16.
ECM Motor Communciations Lost.
This condition
occurs if the furnace control cannot communicate with
the ECM blower motor. The furnace will not operate if
the control cannot communicate with the blower motor.
The diagnostic error code for this condition is
b1
. The
probable cause loose or disconnected wiring between
the motor and control, a failed ECM blower motor (see
section S-16C in
Servicing
), or a failed control.
17.
Motor Horsepower Mismatch.
This condition occurs
if the horsepower of the motor connected to the control
does not match the motor horsepower specified in the
shared data set. The furnace will not operate is there is
a motor horsepower mismatch. The diagnostic error
code for this condition is
b2
.
Verify that the installed motor is the correct motor for
the furnace model. Obtain the correct motor for the
furnace model. Verify the shared data set is correct for
the furnace. The shared data set may be corrected
using the appropriate memory card. Contact your dis-
tributor for the correct memory card. See 13 and 14
above for additional memory card information.
18.
ECM Motor Operating in a Limiting Condition.
This
condition will occur if the ECM operates in a power,
speed, or temperature limiting condition. The furnace
will continue operating at reduced performance. The
diagnostic error code for the this condition is
b3
.
Power Limit.
In attempting to deliver the airflow demand,
the motor may exceed its rated output power. The mo-
tor will reduce its output to prevent exceeding its power
limit. This will result in lower than demanded airflow.
This will occur under high loading conditions. High load-
ing conditions could be due to blocked/clogged filters,
blocked or restrictive ductwork, or undersized ductwork.
Power Limit.
In attempting to deliver the airflow demand,
the motor may exceed its rated output power. The mo-
tor will reduce its output to prevent exceeding its power
limit. This will result in lower than demanded airflow.
This will occur under high loading conditions. High load-
ing conditions could be due to blocked/clogged filters,
blocked or restrictive ductwork, or undersized ductwork.
Speed Limit.
In attempting to deliver the airflow demand,
the motor may exceed its maximum speed of 1500 RPM.
The motor will reduce its speed to prevent exceeding its
maximum. This will result in lower than demanded air-
flow. A blocked inlet, lightly loaded or no load condi-
tions could cause high motor speeds.
Temperature Limit.
In attempting to deliver the airflow
demand, the motor may exceed its temperature limit.
The motor will reduce its output in an attempt to reduce
its temperature. This will result in lower than demanded
airflow. A high ambient temperatue at a high loading
condition is the most probable cause. Reduce the am-
bient temperature and/or motor loading/demand.
19.
Motor Trips.
This condition occurs if the ECM motor
senses a loss of control or becomes overloaded. The
furnace may halt operation if the motor shuts down for a
trip condition. The diagnostic error code for this condi-
tion is
b4
.
Loss of Control (Lost Rotor Trip).
This occurs if a sud-
den change in speed or torque is detected. The motor
will shut down and restart if this condition is encoun-
tered. Possible causes are abnormal loading conditions
due to sudden blockages of the duct system or sudden
high increases in the loading on the motor.
Overload (Current Trip).
This occurs if the motor be-
comes overloaded due to high loading conditions. The
motor will shut down and restart if this condition is en-
countered. High loading conditions could be due to
blocked/clogged filters, blocked or restrictive ductwork,
or undersized ductwork.
20.
Motor Locked Rotor.
This condition occurs if the mo-
tor fails to start after (10) consecutive attempts. The
furnace will not operate if the ECM blower motor fails to
start. The diagnostic error code for this condition is
b5
.
The probable cause is an obstruction in the blower hous-
ing or wheel, siezed motor bearings, or a failed blower
