Service manual

25
Residential Packaged Units - 60Hz Puron
®
ECM Blower Control
The ECM fan is controlled by an interface board that
converts thermostat inputs and fi eld 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
dehumidifi cation mode settings while the unit is powered.
There are four different airfl ow settings from lowest airfl ow
rate (speed tap 1) to the highest airfl ow 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 dehumidifi cation 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 dehumidifi cation mode is selected. Consult
submittal data or specifi cations catalog for the specifi c unit
series and model to correlate speed tap setting to airfl ow in
CFM.
Heating Settings: The heating setting determines the
heating CFM for GT-PX (50YD) and GT-PG (50YE) units.
Tap 1 is the lowest CFM setting, while tap 4 is the highest
CFM setting. Consult submittal data or specifi cations catalog
for the specifi c unit series and model to correlate speed tap
setting to airfl ow 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 specifi cations catalog for the specifi c unit
series and model to correlate speed tap setting to airfl ow 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 airfl ow by +/- 15%. The +/-
settings are used to “fi ne tune” airfl ow 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.
Dehumidifi cation Mode Settings: The dehumidifi cation
mode setting provides fi eld selection of humidity control.
When operating in the normal mode, the cooling airfl ow
settings are determined by the cooling tap setting above.
When dehumidifi cation is enabled there is a reduction in
airfl ow
in cooling to increase the moisture removal of the heat
pump. Consult submittal data or specifi cations catalog for
the specifi c unit series and model to correlate speed tap to
airfl ow in CFM. The dehumidifi cation mode can be enabled in
two ways.
1. Constant Dehumidifi cation Mode: When the
dehumidifi cation 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 airfl ow). Any time the unit is running in
the cooling mode, it will operate at the lower airfl ow
to improve latent capacity. The “DEHUM” LED will be
illuminated at all times. Heating airfl ow is not affected.
NOTE: Do not select dehumidifi cation mode if
cooling setting is tap 1.
2. Automatic (Humidistat-controlled) Dehumidifi cation
Mode: When the dehumidifi cation 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 airfl ow will only be reduced when the
humidistat senses that additional dehumidifi cation 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 dehumidifi cation mode.
Heating airfl ow is not affected. NOTE: Do not select
dehumidifi cation mode if cooling setting is tap 1.