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1−Blower Wheels (all units)
All units have two 18 in. x 15 in. (457 mm x 381 mm) blower
wheels. Both wheels are driven by one motor.
2−Indoor Blower Motor B3 (all units)
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 section in 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.
IMPORTANT
Three phase scroll compressors must be phased se-
quentially for correct compressor and blower rota-
tion. Follow COOLING START−UP" section of instal-
lation instructions to ensure proper compressor and
blower operation.
A−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.
In zone sensor applications the blower will cycle with de-
mand (default). For continuous blower operation change
ECTO 6.17 to option 1. Refer to the IMC manual.
B−Blower Access
1− Disconnect jack/plug connector to blower motor. Also
disconnect jack/plug connector heating limit switches
on units containing gas heat.
2− Remove screws on either side of blower assembly slid-
ing base. See figure 12.
3− Pull base toward outside of unit.
C−Determining Unit CFM
1− The following measurements must be made with a dry
indoor coil. Run blower without a cooling demand.
Measure the indoor blower shaft RPM. 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− Use the tables at the front of this manual to deter-
mine unit CFM.
4− Constant Air Volume (CAV) Supply Air Blowers −
The blower RPM can be adjusted at the motor pulley.
Loosen Allen screw and turn adjustable pulley clock-
wise to increase CFM. Turn counterclockwise to de-
crease CFM. See figure 12. Do not exceed minimum
and maximum number of pulley turns as shown in table
2.
TABLE 2
MINIMUM AND MAXIMUM PULLEY ADJUSTMENT
Belt Minimum Turns Open Maximum Turns Open
A Section No minimum 5
B Section 1* 6
*No minimum number of turns open when B belt is used on
pulleys 6" O.D. or larger.
5− Variable Air Volume (VAV) Supply Air Blowers −
The VFD blower motor pulley is fixed. The supply CFM
can be adjusted at the IMC board or by using optional
software. Refer to the IMC manual ECTO 0.08.
In default mode, the IMC is set to drive the blower to
maximum CFM output (100% or 60Hz). To decrease
the CFM, reduce the VAV maximum output (ECTO
0.08). To increase the CFM, contact Technical Sup-
port.
The default minimum blower output is 50% (30Hz). Re-
fer to ECTO 0.06 and 0.07 to adjust the VAV minimum
output.
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