change operating speeds depending on the room tempera-
ture. If the room temperature is below the set point, the
indoor fan will run at ultra-low speed, and the compressor
could run for up to 4 minutes. (Ultra-low speed is a control-
driven speed [not user configurable] used to sample the space
when the fan would normally be off.) The reversing valve
(619E heat pump units only) will be on. 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.
Initial Operation — When the mode is first selected, one of
the following occurs:
1. If the room temperature is above or equal to the se-
lected temperature, the unit will operate for 16 min-
utes, and the compressor and outdoor fan will operate.
The indoor fan will operate as in the cooling mode. Af-
ter 16 minutes of operation (or when the room reaches
2° F below set point), the unit switches to normal dehu-
midification operation.
2. If the room temperature is below the selected tempera-
ture, the unit will operate for 8 minutes as follows: the
compressor and outdoor fan will operate for 3 minutes.
The indoor fan will operate in low speed, and 30 sec-
onds after the compressor stops, the indoor fan stops.
The unit remains off for 1 minute, and then the indoor
fan starts in ultra-low speed for 30 seconds. The unit
then switches to normal dehumidification operation.
Normal Operation — One of the following will take place:
1. When the temperature of the room is equal to or greater
than the selected temperature (by not more than 3° F),
the unit will operate for 8 minutes as follows: the com-
pressor and outdoor fan will operate for 3 minutes. The
indoor fan will operate in low speed, and 30 seconds af-
ter the compressor stops, the indoor fan stops. The unit
remains off for 1 minute, and then the indoor fan starts
in ultra-low speed for 30 seconds. The normal dehumidi-
fication operation is repeated for the newly sensed room
temperature.
2. If the room temperature is equal to or greater than the
selected temperature, but not by more than between
4° F and 6° F, the compressor and outdoor fan operate
for 4 minutes. The indoor fan will run at ultra-low speed
and will stop 30 seconds after the compressor stops. Af-
ter 3 minutes, the indoor fan runs at ultra-low speed for
30 seconds. The normal dehumidification operation is re-
peated for the newly sensed room temperature.
3. When the room temperature is equal to or greater than
4° F below the selected temperature, the system oper-
ates as follows: The compressor and outdoor fan oper-
ate for 3 minutes. The indoor fan will operate at ultra-
low speed and will stop 30 seconds after the compressor
stops. After 4 or 5 minutes, the indoor fan starts in ultra-
low speed for 30 seconds. The normal dehumidification
operation is repeated for the newly sensed room
temperature. If the room temperature is still 4° F below
the selected temperature, the compressor, outdoor fan,
and indoor fan remain off. After 7
1
⁄
2
minutes, the indoor
fan operates at ultra-low speed for 30 seconds. The nor-
mal dehumidification operation is repeated for the newly
sensed room temperature.
• Heat Pump Heating Mode (Heat Pump Systems Only) —
When the heat pump mode is selected, the indoor fan will
operate at the selected speed if the speed is high, medium,
or low, unless overridden by the coil temperature (to pre-
vent cold drafts). If the indoor fan is in auto. mode, the fan
will change operating speeds depending on the difference
between the room temperature, the set point, and the coil
temperature. The reversing valve will be off. The compres-
sor cannot run for 3 minutes from the time the system starts
up or for 3 minutes from the time it last operated. When
the temperature of the room is 8° F below the selected tem-
perature, the unit will operate in heat pump mode until
the temperature is 6° F above the selected temperature, or
the compressor runs for 40 minutes (whichever comes first).
If the temperature of the room is less than 7° F below or
equal to the selected temperature, the unit operates in heat
pump mode until the selected set point temperature plus
2° F is reached.
• Demand Defrost Mode (Heat Pump Systems Only) — This
unit uses a demand defrost system to remove frost from
the outdoor coil during heating operation. The indoor and
outdoor fans are shut off during defrost mode.
• Sleep Mode — The sleep mode timer will turn the unit off
when the timer reaches zero minutes. During the first
1
1
⁄
2
hours from the time the sleep mode timer starts, the
room temperature is set back from the selected tempera-
ture a total of 4° F in cooling and 6° F in heating (538B only).
• Awake Mode — The awake timer will turn the unit on when
the timer reaches zero minutes. The unit will start in the
same mode and at the same selected temperature as when
the system shut off.
• Automatic Operation Mode for Cooling Only Systems (538A
and 538S) — The unit samples the air in the room. Based
on the room temperature, the unit selects one of the fol-
lowing modes:
1. Cooling Mode — If the room temperature is more than
82.4 F with a preset temperature of 78.8 F.
2. Dry Mode — If the room temperature is more than 75.2 F
and less than 82.4 F with a preset temperature of 77 F.
3. Fan Only Mode — If the room temperature is less than
75.2 F.
The preset temperature can be changed by ±4 F using the
remote control.
• Automatic Operation Mode for Heat Pump Systems (538B)
— The operation mode will be determined after 20 seconds
of room monitoring (to determine the room temperature
and the outdoor air temperature).
• Test Mode — The test mode can be selected by setting the
slide switch on the fan coil unit to TEST position. The slide
switch is located on the front of the unit as shown in
Fig. 20. The fan coil unit will start immediately (there is
no compressor time delay when using test mode) in cool-
ing mode with an infinitely low set point. The indoor fan
speed will be at the high setting, and the swing louvers
will be on (moving up and down).
NOTE:
The unit cannot be controlled by the remote control-
ler until the slide switch is returned to the REMOTE
position.
• Emergency Mode — This mode is only to be used if the re-
mote controller is lost, damaged, or the batteries are dis-
charged. To initiate emergency mode, manually move the
slide switch on the fan coil unit to the EMER position
(Fig. 20). The unit is automatically operated in cooling or
heating (538B units only) mode according to room tem-
perature. Emergency operation settings are as follows:
1. Operation mode: AUTO.
2. Fan Speed: AUTO.
3. Cooling set point: 77 F
4. Timer mode: Continuous
NOTE:
The unit cannot be controlled by the remote control-
ler until the slide switch is returned to the REMOTE
position.
—11—
