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6 Indoor Fan Motor Function
System Operation and Function
This unit can run with either 4 Stage Fan Control or 2 Stage Fan Control.
The factory default is 4 Stage Fan Control. To change the factory default
parameters, refer to the information provided below.
Four Stage Fan Control
When confi gured for 4 stage fan control the fan speed will automatically
change according to the temperature diff erence between T1 (return air
temperature) and Ts (estimated thermostat set point). Higher diff erences
in temperature between T1 and Ts relate to higher fan speeds. This fan
control is supported by either a single or two stage thermostat.
The ECM Constant Torque motor has 5 selectable speed taps. The unit
can use up to 4 fan speeds by setting the SW6-4 dip switch to the "ON"
position (default). For determining the required airfl ow, refer to the
Airfl ow Performance Table (Table 7). To select the fan speeds, change
SW6-1 and SW6-2 dip switches, refer to Table 8 for dip switch speed
confi guration.
Figure 14
SW6-4
SW6-1
SW6-2
OFF
OFF
OFF
ON
ON*
ON*
OFF*
ON
ON
Table 8
*Note: Default Fan Speed is SW6-4 ON, SW6-1 ON, SW6-2 OFF
Two Stage Fan Control
The unit supports two stage fan control which requires a two stage
thermostat (Y1&Y2). When there is a call for Y2, the blower motor will
turn to high speed setting. When there is a call for Y1, the blower motor
will turn to low speed setting. Unit will run at low speed setting when there
is only G call. It will run in high speed setting when there is W/W1/W2
signal (when the electric heat kit is on).
Customers can select two stage fan control by setting the SW6-4 dip
switch to the "OFF" position. Select the two fan speeds using the SW6-1
and SW6-2 dip switches, refer to Table 8. Refer to Airfl ow Performance
Table (Table 7) for reference airfl ow.
If 2 stage thermostat is not available, single stage thermostat may be
used, please refer to Wiring Diagram section for wiring instructions. If Y1
and Y2 are jumped, the unit will only run in high stage fan speed.
Bosch 15 SEER2 Inverter Ducted Packaged Heat Pump - BTC 761701319 A (12.2022)
Mid-
High
Mid
Low
high
2
2
1
3
2
2
4
3
2
5
4
3
SW6-4
SW6-1
OFF
OFF
OFF
ON
ON
Table 9
Anti-Cold Air Fan Delay
The Anti-Cold Air Fan Delay function utilizes a sensor (T2) located on the
indoor coil, which prevents the blower from turning on until the coil has
reached a certain temperature. This feature prevents cold air blow during
heating operation and is activated by setting SW6-3 dip switch to the "ON"
position (default), refer to Figure 14 and Table 10.
1.
When SW6-3 dip switch is set to the "ON" position and the unit is
in heating mode, the Anti-Cold Air Fan Delay function will activate
based on the following entry conditions (all 3 conditions must be
met):
a. Indoor Coil Temperature (T2) < 82.4 °F
b. Electric heat kit is turned off
c. There is a call for Y1 from thermostat to indoor unit
2.
This function will deactivate if ONE OF the following exit conditions
are met OR the system has been operating in heating mode for 15
minutes.
a. T2 ≥ 89.6 °F
b. Heater kit is turned on
c. The system is NOT running Heat mode
3.
During the heating mode, if one of the exit conditions of Anti-Cold
Air is satisfi ed, the blower motor will turn on in fi rst stage fan
speed.
4.
During the heating mode, if all of the entry conditions of Anti-Cold
Air are met and maintained for 120s, the blower motor will change
1
to fi rst stage speed.
1
1
SW6-3
2
ON*
OFF
Table 10
*Note: Default is ON
Heating Fan Delay
If SW6-3 dip switch is set to the "OFF" position (refer to Table 9), and the
unit is in heating mode, the blower will operate with a 90 second delay
with the fan speed dictated by Y1 or Y2 signal.
Passive Dehumidifi cation (Optional)
The unit has a Passive Dehumidifi cation function which lowers the fan
speed and optimizes the compressor operation with a DH call from the
thermostat. This function requires proper DH wiring from the indoor unit
to the thermostat (with a humidistat).
If DH wire is not connected, the unit will still function normally,
but will not be able to run in dehumidification mode.
Installation Instructions
Mid-
SW6-2
High
high
OFF
2
/
ON
3
/
OFF
4
/
ON
5
/
Heat: Anti-Cold Air Fan Delay via Temp Sensor
Heat: Timed Fan Delay
Mid
Low
1
/
1
/
2
/
3
/
| 17
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Troubleshooting
