Product data

Controls — systems using high wall fan coils
40QNB/QNE control system
The 40QN unit is equipped with a microprocessor control, which operates the system. This control is located in the
control box of the fan coil unit, with thermistors located in the fan coil inlet and on the indoor coil. The 40QNE heat
pump fan coil units also have thermistors located on the outdoor coil and in the outdoor air inlet. These thermistors
monitor system operation and control the operating mode. To change settings or modes of operation, use the
factory-supplied infrared wireless remote controller (see Fig #1). This controller allows the fan coil unit to be
operated from within the same room without any wire connections to the unit. The remote controller includes a
wall-mounted bracket. To install the bracket, attach bracket to the wall using factory-supplied, double-sided tape.
Install factory-supplied batteries into the remote controller and place the controller into the bracket so that it is ready
for use.
Operating mode memory
After the system is turned 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 continues in the same operating
mode as when power shut down.
Automatic operation (Auto) mode
If auto mode is selected, the system automatically switches the operating mode from heating to cooling, or from
cooling to heating depending on the preset temperature (adjustable ± 35° F). On cooling only units the Auto mode
automatically switches the operating mode to cooling.
NOTE: Between the cooling cycle and the heating cycle there is a neutral zone of approximately 2° F above and 2°
F below the preset temperature when only the fan is operating.
Operating fault diagnosis
The system includes an automatic diagnosis feature, which is activated under difficult or unacceptable operating
conditions. If such conditions occur, the system stops automatically, the operating fault signal appears (green
‘‘UNIT ON’’ light on the front of the fan coil unit flashes), and an analysis of the system operating conditions is
initiated. The system is restarted automatically as soon as normal conditions have been restored, or after 5 tries it
will remain off. If the system does not start again, the green ‘‘UNIT ON’’ light flashes an error code.
Control operating modes
There are 11 operating modes on Heat Pumps and 9 on Cooling Only Units (including the off mode)
Each mode operates as follows:
• Off Mode — When the unit is in the off mode, all functions (compressor, outdoor fan, indoor fan, and air sweep)
are off, except the reversing valve, which will stay energized if the unit was last operated in the cooling mode.
• Air Circulation Mode (Fan Operation Only) — When air circulation mode is selected, the indoor fan operates
continuously at the selected speed (high, medium, low, or auto). If the auto mode is selected, the indoor fan operates
at low speed. The compressor and outdoor fan are off. The reversing valve will remain in the last operating mode.
• Cooling Mode — When the cooling mode is selected, the indoor fan operates continuously at the selected speed if
the speed is high, medium, or low. If the indoor fan is in auto mode, the fan changes operating speeds depending on
the difference between the room temperature and the set point. The reversing valve will be on for 40QNE018, 024
units or off for 40QNE009, 012 units. The compressor cannot run for 3 minutes from the time the system starts up or
for 3 minutes from the time the compressor last operated. When the temperature of the room is equal to or greater
than the selected temperature, the compressor and outdoor fan will operate until the room temperature is 2° F below
the set point, and then shut off. When the room temperature is less than the selected temperature, the compressor and
outdoor fan remain off. MORE ON NEXT PAGE