Specifications

CONTROLS — SYSTEMS USING CEILING-SUSPENDED OR CASSETTE FAN COILS
AUTOMATIC AIR SWEEP — All 619C units are equipped with
an automatic air sweep feature which automatically directs
the airflow louvers up and down to provide optimum room air cir-
culation. If the auto sweep feature is not desired, temporarily
start the auto sweep using the remote thermostat (press Air
Sweep button). When the louvers are in the desired position,
turn auto sweep off (press Air Sweep button again) to hold them
in that position.
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 the system shut down.
AUTOMATIC OPERATION (AUTO) MODE — If auto mode is
selected, the system automatically switches over the operating
mode from heating to cooling, or from cooling to heating de-
pending on the selected temperature. Auto mode also controls
fan speed if not manually overridden.
NOTE: Between the cooling cycle and the heating cycle there is
a neutral zone of approximately 2° F above and 2° F below the
selected temperature when only the fan is operating.
OPERATING SEQUENCE — Ceiling-suspended fan coil units
have a relay board which controls system operation in response
to the 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 ventilation kit and/or
condensate pump.
Fan Operation — Fan speed can be selected by pressing 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 operate to provide fresh air. If the
mode is set to the AUTO position, then the fan will operate with
the outdoor unit compressor.
Cooling Mode Operation — When the room thermostat
senses a demand for cooling, the fan coil relay board is ener-
gized. The indoor fan(s) will start in the selected speed (if it is
not already operating). The reversing valve will energize and
switch to the cooling position.
The internal condensate pump (if so equipped) runs whenever
the reversing valve is energized and/or the unit is in cooling. As
long as the condensate float switch and freeze protection ther-
mostat are closed, the cooling relays in the fan coil unit will
close. This energizes the compressor and outdoor fan in the
outdoor unit.
The compressor will continue to operate until the room thermo-
stat is satisfied. When the cooling demand is satisfied, the com-
pressor and outdoor fan will stop. If the system is in the AUTO
mode, the indoor fan will stop with the compressor. If the unit
has the accessory ventilation kit, the ventilation fan will operate
whenever the indoor fan is set for medium or high speed.
Heat Pump Operation — 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 oper-
ating), and the reversing valve will not be energized. The inter-
nal condensate pump (if supplied) and freeze protection
thermostat are not operated during heating operation. The con-
trol 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 ener-
gized 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.
Air Sweep
Mode
Fan
Day/Night
Remote Thermostat
80