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Modes of Operation
Standard Digital Touchpad Control
Indoor Air Sensor Reading
To advance from Damper Setting to Indoor Air Sensor
Reading, press the Mode Button once. The control
readout will show room temperature.
Figure 25. Indoor Air and Indoor Coil Sensor Locations
Figure 26. Outdoor Air Sensor Location
Outdoor Air Sensor
(OAS)
Thermistor Failure Code and Condition
The system treats a sensor open or short as extremely
cold or hot and reacts accordingly. The exception is the
room air sensor, in which case the system will turn off.
When the fault is corrected by replacement or repair,
the respective error code will clear from the display (see
Fault & Codes table on page 34).
Compressor Random Restart
When power is interrupted, a random compressor restart
delay of 0 to 2 minutes is initiated. In the Cool Mode only,
the compressor will start operating only after the random
delay plus 2 minutes (minimum off time for thermostat 2
to 4 minutes). Random delay is used only during system
startup or reset.
IM 882 / Page 20 of 36
Unit Protective Logic
Compressor Minimum Run Time
For thermostat-controlled running cycles, the compressor
will have a minimum run time of 90 seconds. The
compressor can be stopped at any time if the system is
switched to any Mode, except the Cool Dry Mode.
Compressor Minimum Off Time
(delay on break)
When compressor is under the thermostat control, it has a
2-minute delay before restarting when it has cycled off.
Indoor
Anti-freeze Protection
Coil Sensor (ICS)
The system is in Anti-freeze Mode when the
following conditions are met:
Indoor
1. The control is in either Cool or Cool/Dry Mode.
Air Sensor (IAS)
2. The indoor coil reaches 30°F and stays there for at
3. The compressor has run for at least 90 seconds.
Sleep Timer is overridden during this operation. Anti-
freeze Protection is active in all modes of operation and
when the control is Off.
In Anti-freeze Mode, the compressor and outdoor fan
will stop, the indoor fan will continue to run and the
display will show "CF".
The compressor and outdoor fan can be started only if the
following conditions are met:
1. after the 2 minute delay on break, AND
2. the indoor coil reaches 49°F or above and remains
3. another Mode is selected.
Room Freeze Protection
When room temperature falls below 41°F, the damper
motor de-energizes, the hydronic valve is opened and
the indoor fan operates on High Speed. The compressor
and outdoor fan are off and the display will show "rF".
The hydronic valve will close and the damper motor will
resume normal operation when the room temperature
rises back to 50°F. During room freeze conditions, the
temperature setting can be adjusted with the touchpad.
Fan modes and Sleep Operation are overridden during
Room Freeze Protection. Room Freeze Protection is
active in all modes of operation and when control is off.
Temperature Limiting
When the room temperature drops 5°F below set
point, the display will indicate "Lo." When the room
temperature rises 5°F above set point, the display will
indicate "hI." Alarm indications of 5°F above or below
set point will be consistent with the configuration settings
for minimum and maximum temperatures.
least five (5) minutes.
there for at least 1 minute, OR
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