LGA/LCA/LHA - lennox

2−Indoor Blower Motor B3 (all units)
All LGA/LCA/LHA units use three-phase single-speed blower
motors. CFM adjustments are made by adjusting the motor
pulley (sheave). Motors are equipped with sealed ball bearings.
All motor specifications are listed in the tables on pages
3, 5, and 6. Units may be equipped with motors manufactured
by various manufacturers, therefore electrical FLA and LRA
specifications will vary. See unit rating plate for information
specific to your unit.
OPERATION / ADJUSTMENT
Blower Operation
NOTE−The following is a generalized procedure and does
not apply to all thermostat control systems.
1− Blower operation is dependent on the thermostat control
system option that has been installed in the LGA/LCA/
LHA units. Refer to operation sequence of the control system
installed for detailed descriptions of blower operation.
2− Generally, blower operation is set at the thermostat fan
switch. With the fan switch in �ON" position and the OCP
input is �ON", the blower operates continuously. With
the fan switch in �AUTO" position, the blower cycles
with demand.
3− In most cases, the blower and entire unit will be off when
the system switch is in the �OFF" position. The only exception
is immediately after a heating demand when the
blower control keeps the blower on until all heat is extracted
from the heat exchanger.
Determining Unit Air Volume
1− The following measurements must be made with a dry indoor
coil. Run blower without cooling demand. Air filters
must be in place when measurements are taken.
BLOWER MAY NEED TO BE
REMOVED TO INSPECT
HEAT EXCHANGER, REAR
BLOWER BEARINGS, ETC.
BLOWER ASSEMBLY
SLIDING BASE
LOOSEN (4) SCREWS TO
ADJUST BELT TENSION
PULLEY
TO DECREASE AIR VOLUME
TURN PULLEY COUNTERCLOCKWISE
TO INCREASE AIR VOLUME
LOOSEN ALLEN SCREW & TURN PULLEY
CLOCKWISE
BLOW-
ER
MOTOR
FIGURE 14
Page 46
2− With all access panels in place, measure static pressure
external to unit (from supply to return).
3− Measure the indoor blower wheel RPM.
4− Refer to blower table on page 10, use static pressure and
RPM readings to determine unit air volume. Use
blower tables on pages 11 and 12 when installing
units with the optional accessories listed.
5− The RPM can be adjusted at the motor pulley. Loosen Allen
screw and turn adjustable pulley clockwise to increase
RPM. Turn counterclockwise to decrease RPM. See figure
14.
Blower Belt Adjustment
Proper pulley alignment and belt tension must be maintained
for maximum belt life.
NOTE−Tension new belt after 24−48 hours of operation.
This will allow belts to stretch and seat in grooves.
1− Loosen four screws securing blower motor to sliding base.
See figure 14.
2− To increase belt tension −
Turn belt tension adjusting screw to the left, or counterclockwise,
to tighten the belt. This increases the distance
between the blower motor and the blower housing.
To loosen belt tension −
Turn the adjusting screw to the right, or clockwise to
loosen belt tension.
3− Tighten four screws securing blower motor to sliding
base once adjustments have been made.
BELT TENSION
ADJUSTING
SCREW
ALLEN
SCREW
REMOVE SCREWS TO
SLIDE BLOWER
ASSEMBLY OUT OF UNIT
TO INCREASE BELT TENSION
1−Loosen four screws securing
blower motor to sliding base.
2−Turn adjusting screw to the left,
or counterclockwise, to move
the motor downward and tighten
the belt.
3−Tighten four screws.
BLOWER
WHEEL BRACK-
ET