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. The discharge louvers on the unit can be stationary or swing continuously. A switch located at the bottom of the unit will turn the swing function on and off.
Ceiling-suspended systems may be equipped with an accessory power ventilation kit and/or condensate pump.
FAN OPERATION — Fan coils are capable of 3-speed operation. See thermostat instructions for fan speed selection. 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.
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 whenever 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 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 thermostat is satisfied. When the cooling demand is satisfied, the compressor 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.
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 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.
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.
The DFB logic checks the 10-minute defrost timer and the DFT. If the DFT opens in less than 10 minutes, the DFB switches the unit back to normal heating operation. If the DFT remains closed, the DFB switches the unit back to heating operation after 10 minutes. When the DFB changes back to heating mode, the RVR (reversing valve relay) is de-energized and the reversing valve switches back to heating operation. Both the outdoor and indoor fans come back on, and if necessary, the electric heater also turns on. SYSTEM
SAFETIES — The system is equipped with the following safety devices to protect system components: Indoor coil freeze protection thermostat — If a coil temperature of 28_F (-2.22_C) or lower is sensed, the compressor and outdoor fan will be shut down until the coil temperature exceeds 28_F (-2.22_C). The indoor fan will continue to run. Condensate float switch (units equipped with accessory condensate pump, cooling cycle only) — If the level of condensate in the drain pan rises too high, the condensate float switch will turn the system off.
CLEANING AND MAINTENANCE
!WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Before installing, modifying, or servicing system, main electrical disconnect switch must be in the OFF position. There may be more than 1 disconnect switch. Lock out and tag switch with a suitable warning label.
!CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage or improper operation.
To avoid shrinkage, do not wash filter in water over 120_F (48.9_C). To avoid damage, do not expose filter to fire or direct sunlight . Clean the filter more frequently when air is extremely dirty.
For proper system operation, perform the cleaning and maintenance operations in Table 13.
Lubrication — The indoor-fan, automatic air sweep, and the outdoor-fan motors are factory lubricated and require no oiling.
AIR FILTERS
!CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage or improper operation.
Operating the system with dirty air filters may damage the indoor unit and can cause reduced cooling performance, intermittent system operation, frost build-up on the indoor coil, and blown fuses. Inspect and clean or replace the air filters monthly.
REMOVE AIR FILTERS — Remove filters by pulling them straight out.
CLEAN OR REPLACE FILTERS — Filters can be vacuumed or washed in warm water. Shake filter to remove any excess water, and replace by sliding filter behind grille until filter snaps in place. Refer to Fig. 32. If the filter has begun to break down or is torn, replace it. Replacement filters are available through your dealer.
