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Eubank 7AA1024A-1060A & 7AA2036A-2060A I&O Manual
07/2021 Rev.3
and the indoor fan remains on continuously but the outdoor fan cycles based on head pressure.
The Fan Cycle Control Switch (Low Ambient Control Switch) closes at 400 PSIG to set the “FCC
IN” input High which in turn outputs a speed proportional to the “OFM Speed” setting on the
board or by MODBUS. This brings on the outdoor fan which runs until the switch reopens (at
290 PSIG). These outputs function as described until the Cooling setpoint is satisfied.
2.1.2
Y2 Cooling (Partial Capacity 50%)
If the space temperature continues to increase pass the defined differential, Stage 2 Cooling (Y2-
input) is energized. Under normal operation, this energizes the Compressor 2 Output (CC2). The
Indoor Fan motor, will operate at “Y2” speed instead of “Y1” speed since Y2 has higher priority.
These outputs remain energized until the cooling setpoint is satisfied. Once the setpoint is satisfied,
the Compressor and the Outdoor fan outputs are de-energized. The Indoor motor continues to run
for 90 seconds after the operation.
2.1.3
Y1 and Y2 Cooling (Full Capacity)
In the event that both Y1 and Y2 inputs are triggered, both CC1 and CC2 outputs are energized
under normal conditions. The Indoor Fan motor, will operate at “Y2 speed” since Y2 has higher
priority. Outputs described in the partial cooling operation above continue to function as described
until the cooling setpoint is satisfied. Once the setpoint is satisfied, the Compressor and the Outdoor
fan outputs are de-energized. The Indoor motor continues to run for 90 seconds after the operation.
Note:
With staged compressors, a CC2 output without a CC1 output will neither result in partial
capacity nor full capacity. Only CC1 output can achieve partial capacity. Both CC1 and CC2
outputs are required to achieve full capacity.
Request
Active Input Active Output
Stage 1 Cooling (1 Fixed Compressor)
Y1
CC1 (Partial Capacity)
Stage 1 Cooling (2 Fixed Compressors)
Y1 or Y2
CC1 or CC2 Respectively (Partial Capacity)
Stage 1 Cooling (1 Staged Compressor)
Y1
CC1 (Partial Capacity)
Stage 2 Cooling (2 Fixed Compressors)
Y1 + Y2
CC1 + CC2 (Full Capacity)
Stage 2 Cooling (2 Staged Compressors)
Y1 + Y2
CC1 + CC2 (Full Capacity)
Stage 2 Cooling (2 Staged Compressors)
Y2
CC1 But the compressors will not run without CC1
being active. No Cooling.
3.0– Heating
3.1– Electric Heat
When there is a request for “Heating (W2-Input High)” via MODBUS, Digital Input or On-board
Thermostat, the HVAC unit will run the Indoor Motor for 10 seconds prior to energizing the Heater
Output. Once the Heater output is energized, the Heater comes on at full capacity (no staging). The
Heater will remain on until the Heating setpoint is satisfied and the request is dropped. Once the heat-
ing setpoint is satisfied, the Indoor Fan will continue to run for 90 seconds while all other associated
outputs are de-energized. Indoor Fan will default at 80% of Y2 speed.
4.0– Dehumidification
4.1– Independent Reheat Output
A request for “Dehumidification (Hum – Input High)” via MODBUS or Digital input will result in
the control board energizing the Compressor 1 (CC1), Compressor 2 (CC2) and the Reheat (RH)
relay outputs on the board. It also produces a continuous control signal for the Indoor Fan Motor that
is proportional to the 80% (default) of the Y2 speed. The Outdoor Fan Motor is request dependent
(based on “FCC IN” Input) and outputs a signal proportional to board or MODBUS setting when the
“FCC IN” input is High. The board continues to produce these outputs until the Dehumidification
request is dropped. Once this request is dropped, the Indoor Fan Motor continues to run for 90 seconds.
