21
OPERATINGSEQUENCE
Ceiling--suspended fan coil units have a relayb oard which controls
systemoperation in response to aroom thermostat. The usermay
manuallyselect any one of 3 fan speeds forunit operation. The
discharge louvers on the unit can be stationary or swing
continuously. A switch located atthe bottom of the unit will turn
theswing function on and off.
Ceiling--suspended systems may be equipped with an accessory
power ventilation kit and/or condensate pump.
FAN OPE RATIO N — 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 sp eed and the unit
is equipped with the power ventilation kit, the ventilation fan will
operateto provide fresh air.
COOLINGMODE OPERATION — When the room thermostat
senses a demand for cooling, the fan coil relay bo ard is energized.
Theindoor fan(s) will startin the selected speed(if it is not already
operating).The reversing valve(heat pump only) will energize for
coolingoperation.
The internalcondensate pump (if so equipped)runs whenever the
reversingvalve is energized(heat pump only) and/or the unit is in
cooling. As long as the condensate float switch and freeze
protectionthermostat are closed,the cooling relays in the fan coil
unit willclose. This energizes the compressorand outdoor fan in
theoutdoor unit.
Thecompressor will continue to operateuntil the room thermostat
is satisfied. When the cooling deman d is satisfied, the compressor
and outdoorfan will stop. If the system is in the AUTO.position,
theindoor fan will stop withthe compressor.
If the unit has the accessory ventilation kit, th e ventilation fan will
operatewhenever the indoorfan is set for medium or high speed.
HEAT PUMP OPERATION — When the room thermostat
sensesa demand for heatingthe indoor fan willstart in the selected
speed(if not alreadyoperating), and thereversing valve willnot be
energized.
The internalcondensate pump (if supplied) and freeze protection
thermostatare not operated during heatingoperation. The control
relay (CR2) closes, and the compressor and outdoor fan are
energizedthrough the defrostboard (DFB), which islocated in the
outdoor unit. The microprocessorlogic in the DFB is energized
whenthe compressor starts, and the defrosttimer runs. Once every
90 minutes (factorydefault setting) of compressor run time,the
DFB logic checks the defrost thermo stat (DFT). If the DFT is
open,the unit continues in heating operation. If the DFT is closed,
theDFB switches the unit to defrostmode. The timing on the DFB
maybe set at either 30, 50, or 90 minutes.
DEFROST (Heat Pump Only) — The DFB energizesthe RVS
(reversingvalve solenoid), andthe reversing valve switchesto the
coolingposition. The K1 relay on theDFB opens and the outdoor
fan stops. The W2 contact on the DFB is also energized , which in
turnenergizesthe defrost relay on thefan coil relay board, turnsoff
theelectric heaterand stops the indoor fan.
TheDFB logic checks the 10--minutedefrost timerand the DFT. If
theDFT opens in less than 10 minutes,the DFB switches the unit
back to normal heating operation. If the DFT remains closed ,th e
DFB switchesthe unit back to heatingoperation after 10minutes.
Whenthe DFB changes back to heatingmode, the RVR (reversing
valve relay) is de--energizedand the rev ersing valve switches back
toheating operation. Both the outdoorand indoor fans come back
on, and if necessary, the electric heater also turns on. SYS TEM
SAFETIES — The system is equipped with the follo wing safety
devices to protect system components: Indoor coil freeze
protectionthermostat— If a coil temperatureof 28_F (--2.22_C)or
loweris sensed, the compressorand outdoor fan will be shut down
until the coil temperature exceeds 28_F (--2.22_C).The indoor fan
willcontinue to run. Condensatefloat switch (units equipped with
accessory condensatepump, cooling cycle only) — If the level of
condensate in the drainpan rises too high, the condensate float
switch will turn the system off.
CLEANING AND MAINTENANCE
!WARNING
ELECTRICALSHOCK HAZARD
Failureto follow this warning could result inpersonal
injuryor death.
Before installing, modifying, or serv icing 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
!
UNITDAMAGE HAZARD
Failure to follow this caution may result in equipment
damageor improper operation.
To avoid shrinkage, do not wash filter in water over
120_F(48.9_C). Toavoiddamage, do not expose filterto
fire or direct sunlight . Clean thefilter morefreq uently
when air is extremely dirty.
For proper system operation, perform the cleaning and
maintenanceoperationsin Table 13.
Lubrication — The indoor--fan, automatic air sweep, and the
outdoor--fanmotorsare factorylubricated and requireno oiling.

AIR FILTERS

CAUTION
!
UNITDAMAGE HAZARD
Failure to follow this caution may result in equ ipment
damageor improper operation.
Operating the system with dirty air filters may damage the
indoor unit and can cause reducedcooling performance,
intermittent system operation, frost build --upon the indoor
coil, and blown fuses. Inspect and clean or replace the air
filtersm onthly.
REMOVE AIR FILTERS — Remove filters by pulling them
straightout.
CLEAN OR REPLACE FILTERS— Filterscan be v acuumed
or washed in warm water.S hake filterto remo vean y excessw ater,
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.
40QAC/38HDR -- 40QAQ/38QR
R