Lennox ALLIED Commercial TCA180S2B Standard Manual page 27

C−Blower Compartment
The blower compartment in TCA180/300 units is located
between the evaporator coil and the compressor / control sec-
tion on the opposite side of the condenser coil. The blower as-
sembly is accessed by removing the screws on either side of
the sliding base. The base pulls out as shown in figure 11.
1−Blower Wheels
All TCA180/300 units have two 15 in. x 15 in. (381 mm x 381
mm) blower wheels. Both wheels are driven by one motor
mounted on a single shaft. Shaft bearings are equipped with
grease ports for service.
2−Indoor Blower Motor B3
All 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 spec-
ifications are listed in the SPECIFICATIONS (table of con-
tents) in the front of this manual. 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
Initiate blower demand at thermostat according to instruc-
tions provided with thermostat. Unit will cycle on thermostat
demand. The following steps apply to applications using a
typical electro−mechanical thermostat.
1− Blower operation is manually set at the thermostat sub-
base fan switch. With fan switch in ON position, blow-
ers will operate continuously.
2− With fan switch in AUTO position, the blowers will cycle
with demand. Blowers and entire unit will be off when
system switch is in OFF position.
Blower Access
The blower assembly is secured to a sliding base which al-
lows the entire assembly to be pulled out of the unit. See
figure 11.
1− Remove the clamp which secures the blower wiring to
the blower motor base.
2− Remove and retain screws on either side of sliding
base. Pull base toward outside of unit. When pulling
the base out further than 12" (305mm), disconnect wir-
ing to K3 blower contactor T1, T2, and T3. Pull wiring
toward blower to allow enough slack to slide the base
out further.
3− Slide base back into original position when finished
servicing. Replace the clamp and blower wiring in the
previous location on the blower motor base. Recon-
nect wiring to K3 if it was disconnected.
4− Replace retained screws on either side of the sliding
base.
Determining Unit Air Volume
1− The following measurements must be made with a dry in-
door coil. Run blower without cooling demand. Air filters
must be in place when measurements are taken.
2− With all access panels in place, measure static pres-
sure external to unit (from supply to return).
3− Measure the indoor blower wheel RPM.
4− Refer to blower tables in BLOWER DATA (table of con-
tents) in the front of this manual. Use static pressure and
RPM readings to determine unit air volume.
5− The RPM can be adjusted at the motor pulley. Loosen Al-
len screw and turn adjustable pulley clockwise to increase
RPM. Turn counterclockwise to decrease RPM. Seefigure
11 for TCA180/300 units.
Blower Belt Adjustment
Maximum life and wear can be obtained from belts only if
proper pulley alignment and belt tension are main-
tained. Tension new belts after a 24−48 hour period of
operation. This will allow belt to stretch and seat
grooves. Make sure blower and motor pulley are aligned as
shown in figure 9.
PULLEY ALIGNMENT
BLOWER
PULLEY
1− Loosen four bolts securing motor base to mounting
frame. See figure 11.
2− To relieve belt tension −
Turn adjusting bolt to the right, or clockwise, to move
the motor upward and loosen the belt. This decreases
the distance between the blower motor pulley and the
blower housing pulley.
3− Tighten four bolts securing motor base to mounting
frame.
IMPORTANT − Align top edges of blower motor base and
mounting frame base parallel before tightening two bolts on
the other side of base. Motor shaft and blower shaft must
be parallel.
Page 27
ALIGNED
MOTOR
PULLEY
BELT
NOT ALIGNED
FIGURE 9