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B- Indoor Blower
1. Secondary Limit Control (S21)
The secondary limit (S21) is located in the blower com-
partment. See FIGURE 1. When excess heat is sensed in
the blower compartment, the limit will open. If the limit is
open, the furnace control energizes the supply air blower
and closes the gas valve. The limit automatically resets
when unit temperature returns to normal. The switch must
reset within three minutes or the SureLight control will go
into Watch guard for one hour. The switch is factory set
and cannot be adjusted.
EL280DFE units are equipped with a constant torque
ECM motor. It has a DC motor coupled to an electronic
control module both contained in the same motor housing.
The motor is programmed to provide constant torque at
each of the five selectable speed taps. Each tap requires
24 volts to energize.
Input Voltage Requirements
The circuit is designed to be operated with AC voltage. To
enable a tap requires 12 to 33VAC. Expected current draw
will be less than 20mA.
Troubleshooting the Motor
Troubleshooting the motor is an easy process. Follow
steps below.
1- Shut off power to unit.
2- Remove input plugs P48 and P49 from motor. See
FIGURE 9 for troubleshooting procedure.
If correct voltage is present in tests 1 and 2 and motor
is not operating properly, replace motor. The motor is not
field repairable.
If replacing the indoor blower motor or blower wheel is
necessary, placement is critical. The blower wheel must
be centered in the blower housing as shown in figure 6.
When replacing the indoor blower motor the set screw
must be aligned and tightened with the motor shaft as
shown in FIGURE 8.
BLOWER WHEEL REPLACEMENT
ALIGN AND TIGHTEN SET SCREW WITH
FLAT SIDE OF MOTOR SHAFT
Set Screw
Housing Hub
Motor
Shaft
Page 14
Center Blower Wheel
in Blower Housing
FIGURE 7
FIGURE 8
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