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OPERATING SEQUENCE (cont)
• Maximum Dehumidification Mode — When the dehumidifica-
tion mode is selected, the indoor fan will operate continuously
at the selected speed if the speed is high, medium, or low. If
the indoor fan is in auto. mode, the fan will change operating
speeds depending on the room temperature. If the room tem-
perature 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 config-
urable] used to sample the space when the fan would nor-
mally 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 selected
temperature, the unit will operate for 16 minutes, and the
compressor and outdoor fan will operate. The indoor fan will
operate as in the cooling mode. After 16 minutes of operation
(or when the room reaches 2° F below set point), the unit
switches to normal dehumidification operation.
2. If the room temperature is below the selected temperature,
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 seconds 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 sec-
onds. 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 compressor and
outdoor fan will operate for 3 minutes. The indoor fan will op-
erate in low speed, and 30 seconds 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 sec-
onds. The normal dehumidification operation is repeated for
the newly sensed room temperature.
2. If the room temperature is equal to or greater than the se-
lected 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. After 3 minutes, the
indoor fan runs at ultra-low speed for 30 seconds. The nor-
mal dehumidification operation is repeated 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 operates as fol-
lows: The compressor and outdoor fan operate for 3 min-
utes. The indoor fan will operate at ultra-low speed and will
stop 30 seconds after the compressor stops.After 4 or 5 min-
utes, 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
normal 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 op-
erate at the selected speed if the speed is high, medium, or
low, unless overridden by the coil temperature (to prevent
cold drafts). If the indoor fan is in auto. mode, the fan will
change operating speeds depending on the difference be-
tween the room temperature, the set point, and the coil tem-
perature. The reversing valve will be off. The compressor
cannot run for 3 minutes from the time the system starts up or
for 3 minutes from the time it last operated. When the tem-
perature of the room is 8° F below the selected temperature,
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 tempera-
ture of the room is less than 7° F below or equal to the se-
lected 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. See Electronic Control
Defrost Regions map on page 30 for defrost region details.
• 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 (538D 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 sys-
tem shut off.
• Automatic Operation Mode for Cooling Only Systems — The
unit samples the air in the room. Based on the room tempera-
ture, the unit selects one of the following 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 re-
mote 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. The fan coil unit will
start immediately (there is no compressor time delay when us-
ing test mode) in cooling 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 controller
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. The unit
is automatically operated in cooling or heating (538D units
only) mode according to room temperature. Emergency op-
eration 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 controller
until the slide switch is returned to the REMOTE position.
29