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15
ENVISION SERIES AIR HANDLER INSTALLATION MANUAL
ECM Blower Control
The ECM blower motor is controlled by an interface board
installed in the air handler and allows field selectable CFM
settings. The interface board receives inputs from the
thermostat and converts them to signals used by the ECM
motor. There are four different airflow settings that are field
selectable via DIP switches (see Blower Performance table).
Cooling/Heating settings
The cooling/heating CFM settings determine the normal
cooling/heating CFM when the unit is not in dehumidifica-
tion mode or auxiliary heat mode. DIP switches 1 and 2 ‘off’
is the lowest CFM setting while with DIP switches 1 and 2
‘on’ is the highest CFM setting. To prevent air coil freeze up,
the lowest CFM setting can not be used when dehumidifica-
tion mode is selected. DIP 9 must be ‘on’ to enable normal
airflow settings.
Dehumidification Mode settings
This setting provides for field selection of humidity control
(via setting DIP 9 ‘off’). The cooling airflow settings are de-
termined by the Cooling/Heating DIP switch settings above.
Dehumidification mode reduces the selected normal cooling
CFM by 15%-20% which increases the moisture removing
capability of the heat pump. To prevent air coil freeze up,
the lowest CFM setting can not be used when dehumidifica-
tion mode is selected.
Dehumidification Mode (Continuous) – This mode is se-
lected via setting DIP 9 ‘off’ on the ECM interface board and
will be engaged whenever an ‘O’ input is present. In this
mode any time the unit is operating in cooling mode, it will
run at a CFM level 15%-20% lower than the selected normal
cooling CFM.
NOTE: Do not select dehumidification mode if the lowest
Cooling/Heating airflow level is selected (DIPS 1 & 2 off).
Auxiliary Heat settings - DIP 5 & 6 on the ECM interface
board are used to select the desired CFM in auxiliary/emer-
gency heat mode. Whenever auxiliary or emergency elec-
tric heat is energized this air flow setting will be used.