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LEGEND
DFB — Defrost Board
DFT — Defrost Thermostat
TB
— Terminal Block
Fig. 21 — Heat Pump System Thermostat Wiring
Fig. 22 — Inserting Water into Drain Pan
Adjusting Airflow
AUTOMATIC AIR SWEEP — All units are equipped with
an automatic air sweep feature which automatically directs
the airflow louvers up and down to provide optimum room
air circulation. If the auto. sweep feature is not desired, tem-
porarily start the auto. sweep using the remote thermostat
(press Air Sweep button). When the louvers are in the de-
sired position, turn the auto. sweep off (press Air Sweep but-
ton again) to hold them in that position.
Operating Mode Memory —
off or after a power failure, the system remains in the last
operating mode selected. When the system is turned back
on, or when power is automatically restored, operation con-
tinues in the same operating mode as when the system shut
down.
Automatic Operation (Auto.) Mode —
is selected, the system automatically switches over the 40QAE
operating mode from heating to cooling, or from cooling to
heating (heat pump system only) depending on the selected
temperature. Auto. mode also controls fan speed if not manu-
ally overridden.
NOTE: Between the cooling cycle and the heating cycle there
is a neutral zone of approximately 2° F above and 2° F be-
low the selected temperature when only the fan is operating.
Operating Sequence —
have a relay board which controls system operation in re-
sponse to a room thermostat. The user may manually select
any one of 3 fan speeds for unit operation. Ceiling-suspended
systems may be equipped with an accessory power ventila-
tion kit and/or condensate pump.
FAN OPERATION — Fan speed can be selected by press-
ing the fan button (high, medium, or low speed choices).
The fan(s) is capable of operation when unit mode is set on
either cooling, heating, or auto. mode. When the fan(s) is
operating in medium or high speed and the unit is equipped
with the power ventilation kit, the ventilation fan will op-
erate to provide fresh air. If the mode is set to the AUTO.
position, then the fan will operate with the outdoor unit com-
pressor.
COOLING MODE OPERATION — When the room ther-
mostat senses a demand for cooling, the fan coil relay board
is energized. The indoor fan(s) will start in the selected speed
(if it is not already operating). The reversing valve (40QAE
only) will energize and switch to the cooling position.
The internal condensate pump (if so equipped) runs when-
ever the reversing valve is energized (40QAE only) and/or
the unit is in cooling. As long as the condensate float switch
and freeze protection thermostat are closed, the cooling re-
lays in the fan coil unit will close. This energizes the com-
pressor and outdoor fan in the outdoor unit.
The compressor will continue to operate until the room
thermostat is satisfied. When the cooling demand is satis-
fied, the compressor and outdoor fan will stop. If the out-
door unit is equipped with accessory Time Guard device,
the unit will not allow a new call for cooling for 5 minutes.
If the system is in the AUTO. position, the indoor fan will
stop with the compressor. If the unit has the accessory ven-
tilation kit, the ventilation fan will operate whenever the in-
door fan is set for medium or high speed.
HEAT PUMP OPERATION (40QAE Only) — When the room
thermostat senses a demand for heating, the fan coil relay
board is energized. The indoor fan will start in the selected
speed (if not already operating), and the reversing valve will
not be energized. The internal condensate pump (if sup-
plied) and freeze protection thermostat are not operated dur-
ing heating operation. The control relay (CR2) closes, and
the compressor and outdoor fan are energized through the
defrost board (DFB), which is located in the outdoor unit.
The microprocessor logic in the DFB is energized when the
compressor starts, and the defrost timer runs. Once every
90 minutes (factory default setting) of compressor run time,
the DFB logic checks the defrost thermostat (DFT). If the
DFT is open, the unit continues in heating operation. If the
DFT is closed, the DFB switches the unit to defrost mode.
The timing on the DFB may be set at either 30, 50, or 90
minutes.
14
After the system is turned
If auto. mode
Ceiling-suspended fan coil units
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