—18—
START-UP
Make the following checks and complete the Start-Up Check-
list on page CL-1 before system start-up. Also refer to
the condensing unit Installation, Start-Up and Service
Instructions for system start-up instructions and refrigerant
charging methods.
1. Check condensate drainage system:
a. Remove grille and frame from the unit.
b. On the opposite side of the drain connection,
insert a water bottle up into the fan coil unit and
fill drain pan. Refer to Fig. 22. Water must flow
steadily; if not, check the pipe slope or inspect for
any pipe restrictions.
2. Make sure that all wiring connections are correct and
that they are tight.
3. Check that all barriers, covers, and panels are in
place. Ensure that the filters and return-air grilles
have been installed and that the discharge louvers
are positioned correctly.
I. AFTER EXTENDED SHUTDOWN
If the system has been turned off for more than 12 hours and
a crankcase heater is being used, turn on the indoor and
outdoor unit disconnect switches to supply power to the
system for 12 hours BEFORE starting the system.
II. SEASONAL CHANGEOVERS
When changing heat pump system from cooling to heating or
heating to cooling, or before starting cooling only system
after it has been out of use for the winter season, perform the
following steps BEFORE starting the system:
1. Inspect and clean the outdoor unit, particularly the
coil.
2. Clean or replace the air filters in the indoor unit.
3. Clean the indoor unit drain pan and drain pipe, and
remove any obstructions.
4. If the outdoor unit is equipped with a crankcase
heater, turn on indoor and outdoor unit disconnect
switches to supply power to the system 12 hours
before starting the system.
III. ADJUSTING AIRFLOW
A. Automatic Air Sweep
All units are equipped with an air sweep feature which
directs the airflow louvers up and down to provide optimum
room air circulation. The air sweep function can be con-
trolled by the toggle switch located on the lower right corner
of the unit. If using a thermostat with an air sweep switch,
see Fig. 20 and 21 for wiring modifications.
IV. 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 automati-
cally restored, operation continues in the same operating
mode as when the system shut down.
V. 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 (heat pump system only) depending 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.
VI. OPERATING SEQUENCE
Ceiling-suspended fan coil units have a relay board which
controls system operation in response 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 ventilation kit and/or condensate
pump.
A. Fan Operation
Fan coils are capable of 3-speed operation. See thermostat
instructions for fan speed selection. When the fan(s) is oper-
ating in medium or high speed and the unit is equipped with
the power ventilation kit, the ventilation fan will operate to
provide fresh air.
B. Cooling Mode Operation
When the room thermostat 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 (heat pump only) will energize for cooling
operation.
The internal condensate pump (if so equipped) runs when-
ever the reversing valve is energized (heat pump only) and/
or the unit is in cooling. As long as the condensate float
switch and freeze protection thermostat are closed, the cool-
ing relays in the fan coil unit will close. This energizes the
compressor and outdoor fan in the outdoor unit. The com-
pressor will continue to operate until the room thermostat is
satisfied. When the cooling demand is satisfied, the compres-
sor and outdoor fan will stop. If the system is in the AUTO.
position, 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.
C. Heat Pump Operation
When the room thermostat senses a demand for heating 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 supplied) and freeze
protection thermostat are not operated during heating
operation. The control relay (CR2) closes, and the compres-
sor and outdoor fan are energized through the defrost board
(DFB), which is located in the outdoor unit. The microproces-
sor 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.
D. Defrost (Heat Pump Only)
The DFB energizes the RVS (reversing valve solenoid), and
the reversing valve switches to the cooling position. The K1
relay on the DFB opens and the outdoor fan stops. The W2
contact on the DFB is also energized, which in turn
energizes the defrost relay on the fan coil relay board, turns
off the electric heater and stops the indoor fan.
WARNING:
Never operate unit without a filter or
with grille removed; damage to the unit or personal
injury may result.
