R e s i d e n t i a l H & V - 6 0 H z H F C - 4 1 0 A :
R e v : O c t o b e r 5 , 2 0 2 1
30
G e o t h e r m a l H e a t i n g a n d Co o l i n g
ECM Blower Control
The ECM fan is controlled by an interface board that
converts thermostat inputs and field selectable CFM
settings to signals used by the ECM motor controller.
Units manufactured before July 2005 have version I (P/N
69243707). Units manufactured after July 2005 have version
II (P/N 17B0019N01). Fan speeds are selected with jumpers
for version I or via a nine position DIP switch for version II. To
take full advantage of the ECM motor features, a multi-stage
thermostat should be used (2-stage heat/2-stage cool or
3-stage heat/2-stage cool).
HFC-410A packaged units built after May 2009 have ECM
controller version III (P/N 17B0034N01). This controller
includes logic and a relay to control the HWG functions.
Note: Power must be off to the unit for at least three seconds
before the ECM motor will recognize a speed change.
The motor will recognize a change in the CFM Adjust or
dehumidification mode settings while the unit is powered.
There are four different airflow settings from lowest airflow
rate (speed tap 1) to the highest airflow rate (speed tap 4).
The charts below indicate settings for both versions of the
ECM interface board, followed by detailed information for
each setting.
Cooling Settings: The cooling setting determines the cooling
(normal) CFM for all units with ECM motor. Cooling (normal)
setting is used when the unit is not in dehumidification mode.
Tap 1 is the lowest CFM setting, while tap 4 is the highest
CFM setting. To avoid air coil freeze-up, tap 1 may not
be used if the dehumidification mode is selected. Consult
submittal data or specifications catalog for the specific unit
series and model to correlate speed tap setting to airflow in
CFM.
Heating Settings: The heating setting determines the heating
CFM for Tranquility® 20 (TS) units. Tap 1 is the lowest CFM
setting, while tap 4 is the highest CFM setting. Consult
submittal data or specifications catalog for the specific unit
series and model to correlate speed tap setting to airflow in
CFM.
Auxiliary/Emergency Heat Settings: The auxiliary/emergency
heat setting determines the CFM when the unit is in auxiliary
heat or emergency heat mode. This setting is used for
residential units with internal electric heat. When auxiliary
electric heat is energized (i.e. compressor and electric heat),
the greater of the auxiliary/emergency or heating settingwill
be used. A “G” (fan) signal must be present from the
thermostat for electric heat to operate. Consult the submittal
data or specifications catalog for the specific unit series and
model to correlate speed tap setting to airflow in CFM.
CFM Adjust Settings: The CFM adjust setting allows four
selections. The NORM setting is the factory default position.
The + or – settings adjust the airflow by +/- 15%. The +/-
settings are used to “fine tune” airflow adjustments. The
TEST setting runs the ECM motor at 70% torque, which
causes the motor to operate like a standard PSC motor, and
disables the CFM counter.
Dehumidification Mode Settings: The dehumidification mode
setting provides field selection of humidity control. When
operating in the normal mode, the cooling airflow settings
are determined by the cooling tap setting above. When
dehumidification is enabled there is a reduction in airflow
in cooling to increase the moisture removal of the heat
pump. Consult submittal data or specifications catalog for
the specific unit series and model to correlate speed tap to
airflow in CFM. The dehumidification mode can be enabled in
two ways.
1. Constant Dehumidification Mode: When the
dehumidification mode is selected (via DIP switch or
jumper setting), the ECM motor will operate with a
multiplier applied to the cooling CFM settings (approx.
20-25% lower airflow). Any time the unit is running in
the cooling mode, it will operate at the lower airflow
to improve latent capacity. The “DEHUM” LED will be
illuminated at all times. Heating airflow is not affected.
NOTE: Do not select dehumidification mode if cooling
setting is tap 1.
2. Automatic (Humidistat-controlled) Dehumidification
Mode: When the dehumidification mode is selected
(via DIP switch or jumper setting) AND a humidistat is
connected to terminal DH (version II) or HUM (version
I), the cooling airflow will only be reduced when the
humidistat senses that additional dehumidification is
required. The DH (or HUM) terminal is reverse logic.
Therefore, a humidistat (not dehumidistat) is required.
The “DEHUM” LED will be illuminated only when
the humidistat is calling for dehumidification mode.
Heating airflow is not affected.
NOTE: Do not select
dehumidification mode if cooling setting is tap 1.
