Manual 2100-715B
Page
24 of 25
TABLE 9
Recommended Airflow
Model
Nominal
Rated
CFM*
Nominal
Rated
ESP*
Recommended
Airflow Range
Factory
Speed
Connection
W12AB
425
0.1
350 - 475
Default
* Rated CFM and ESP on factory speed connection.
Setting Unit Airflow
The unit is set from the factory at the default speed.
The unit has two selectable cooling speed taps that
can be utilized. The default speed is the lowest cooling
speed. The higher speed tap can be used for higher
duct static applications so that the unit can maintain
the recommended airflow as shown in Table 9. The
higher speed can also be used when higher sensible
cooling is desired. To change to the higher speed tap,
replace the blue wire on the blower relay with the black
wire. Refer to Table 11 for the corresponding airflow of
each tap. Set the unit duct static based on the highest
airflow that the unit will run at.
NOTE:
Be sure to adjust the system static or
blower speed to maintain airflows above the
minimum recommendations to prevent freeze
up conditions if Balanced Climate mode is
activated.
Do not operate the unit in Balanced Climate mode
if running high static applications as indicated in
the blower performance table. If Balanced Climate
mode is activated as described on page 13, the unit
will run in this mode at all times unless there is a
call for ventilation, electric heat or 2nd stage cooling
from a 2-stage thermostat. At that time, the unit will
automatically activate a higher speed tap.
Blower Speeds
The ECM motor blower has three direct taps that
are available for the motor, and are selected through
different unit modes of operation. These modes are
energized by 24VAC signals from the low voltage
terminal block located inside the control panel by a
thermostat or other controlling device.
Multiple motor speed taps may be energized
simultaneously by 24VAC power during different modes
of operation. The highest number speed tap energized
takes priority with 3 being the highest and 1 being
the lowest. See Table 10 for the corresponding blower
speeds with the different modes of operation.
Speed Tap 1 – Balanced Climate
Speed tap 1 is set as a lower than rated speed in the
ECM motor. In order for Balanced Climate speed to
be used during compressor cooling mode, the jumper
between Y1 and Y2 must be removed. This means that
if speed tap 1 is energized, the airflow amount will be
lower than default airflow. Tap 1 is used when Balanced
Climate is called for by energizing the Y1 terminal of
the low voltage terminal block with 24VAC. Speed tap
1 is overridden if taps 2 or 3 are energized.
Speed Tap 2 – Default Cooling & Heating
Speed tap 2 is set for rated speed in the motor. This
means that if speed tap 2 is energized, the airflow
amount will be the default airflow. Tap 2 is used by
default when cooling is called for by energizing the Y1
terminal of the low voltage terminal block with 24VAC.
The unit is shipped with the jumper between Y1 and
Y2 installed and it must be removed to use Balanced
Climate mode.
Speed Tap 3 – Optional HI Cooling & Heating
Speed tap 3 is set to the highest speed in the ECM
motor. This is a user-selectable airflow amount that
will provide the highest rated airflow. Tap 3 is used for
cooling operation if the blue wire is replaced with the
black wire on the blower relay.
Unit
Operation
Thermostat Inputs – 24VAC
Speed Taps
Blower Speed
Compressor
Operation
G
Y1
Y2
W1
A
D
1
2-3
1
Blower Only
X
X
Vent/Blower Only
Off
Balanced Climate Cooling
X
X
X
Balanced Climate
On
Full Load Cool
X
X
X
X
X
Lo/Hi
On
1st Stage Heat
X
X
Lo/Hi
Off
¹
Fan speed is selectable through the blower relay. LO (default) or HI speeds can be used.
TABLE 10
Blower Speeds for Unit Operational Modes
