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Blower Operation and Adjustments
IMPORTANT
Three phase scroll compressors must be phased
sequentially for correct compressor and blower
rotation. Follow “COOLING START-UP” section of
installation instructions to ensure proper compres
sor and blower operation.
A-Blower Operation
Initiate blower demand at thermostat according to
instructions 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
subbase fan switch. With fan switch in
ON
position,
blowers 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
demand (default). For continuous blower operation
change ECTO 6.17 to option 1. Refer to the IMC manual.
B-Blower Access
1- Remove screws on either side of blower assembly
sliding base. See figure 20, 21, or 22.
2- Pull base toward outside of unit.
C-Determining Unit CFM (with wet coil)
1- Run blower with 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
pressure external to unit (from supply to return).
3- Referring to tables 2 through 5, use static pressure
and RPM readings to determine 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
clockwise to increase CFM. Turn counterclockwise to
decrease CFM. See figure 20, 21, or 22. Do not
exceed minimum and maximum number of pulley
turns as shown in table 1.
TABLE 1
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.
FIGURE 20
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.
TO INCREASE CFM
LOOSEN ALLEN SCREW &
TURN PULLEY CLOCKWISE
TO DECREASE CFM
TURN PULLEY
COUNTERCLOCKWISE
BLOWER
WHEEL
BLOWER
MOTOR
MOTOR
PULLEY
ALLEN
SCREW
BLOWER ASSEMBLY
SLIDING BASE
BELT TENSION
ADJUSTING
SCREW
LOOSEN (4)
SCREWS TO
ADJUST BELT
TENSION
REMOVE SCREWS TO SLIDE
BLOWER ASSEMBLY OUT OF UNIT
BLOWER ASSEMBLY (SW 036 & 060)
BLOWER
PULLEY
PULLEY
ADJUSTMENT
BOLTS
