Carrier COBRA 48/50HJ004-014 - Manual (Page 33)

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2 is selected, 72 F actual will read 74 F. If set point is 72 F, the
room will control to an actual temperature of 70 F which will
be displayed and acted upon as if it were 72 F. The effect is that
a positive number selection will make the room temperature
lower and vice versa. The Light Commercial Thermidistat is
calibrated within an accuracy of plus or minus 1 degree when
shipped from the factory, so this adjustment will provide the
best accuracy when set to 0.
TO SELECT:
1. Enter Configuration mode. Use up and down set point
buttons to make small display (now flashing) indicate 13.
2. Press SET TIME/TEMP button once to flash large display.
3. Use up or down set point buttons to move between –5,
–4, –3, –2, –1, 0, 1, 2, 3, 4, or 5 on large display. Factory
default is 0.
4. Press SET TIME/TEMP button again to flash small
upper display for selection of another option, or press
HOLD End to exit Configuration mode.
Option 14 — Heat/Cool Deadband Adjustment — This op-
tion selects the minimum difference between heating and cool-
ing set points. A larger difference saves energy and a smaller
difference decreases temperature difference between heating
and cooling. Factory default is 2, which means cooling set
point must be a minimum of 2 degrees above heating set point.
An attempt to move them closer will result in one “pushing”
the other to maintain the required difference.
Depending on set points, moving deadband closer than
2 degrees may result in regular cycling between heat and cool
when AUTO mode is selected. However, this cycling cannot
occur more often than 1 transition every 10 minutes. The sys-
tem has a built-in requirement that it cannot switch between
heat and cool without a 10-minute “off” time between the 2
operations. Specifically, to switch from one mode to the other,
there must be no demand for the old mode and a demand for
the new mode, and this must exist continually for 10 minutes
before transition to the new mode will occur.
TO SELECT:
1. Enter Configuration mode if not already there. Use up
and down set point buttons to make small display (now
flashing) indicate 14.
2. Press SET TIME/TEMP button once to flash large
display.
3. Use up or down set point buttons to move between 0, 1, 2,
3, 4, 5, or 6 on large display. Factory default is 2.
4. Press SET TIME/TEMP button again to flash small
upper display for selection of another option, or press
HOLD End to exit Configuration mode.
Option 21 — Keyboard Lock — This option allows the
installer to disable the thermostat from being changed.
TO SELECT:
1. Enter Configuration mode. Use up and down set point
buttons to make small display (now flashing) indicate 21.
2. Press SET TIME/TEMP button once to flash large
display.
3. Use up and down set point buttons to move between OF
and ON on large display. Factory default is OF, keyboard
is active.
NOTE: Once the keyboard is locked the building manag-
er can momentarily unlock the keyboard by pressing the
following keys sequentially, MODE, COPY PREVIOUS
DAY, SET TIME/TEMP, and HOLD End. The sequence
must be completed within a 5-second period, and the
keypad will be unlocked. The keypad will return to lock
once the keypad is idle for a 2-minute period or immedi-
ately if after exiting the Configuration mode.
4. Press SET TIME/TEMP button again to flash upper
small display for selection of another option, or press
HOLD End to exit Configuration mode.
Step 5 — Conduct Light Commercial Thermi-
distat Start-Up and Checkout —
The Light Com-
mercial Thermidistat is designed with a built-in installer test
capability. It allows easy operation of equipment without
delays or set point adjustments to force heating or cooling. To
enable Installer Test mode, move DIP switch no. 4 to ON posi-
tion. To access this switch, open case as described in Step 2 —
Set DIP Switches. Use the tip of a small screwdriver to slide
switch no. 4 to ON position.
While in Installer Test mode, clock will display “InSt,” FAN
button will control fan, and MODE button will control heating
and cooling.
TO TEST FAN:
NOTE: In the Installer Test mode the fan operation is not
dependent on the occupied signal.
Fan button switches FAN icon between AUTO and ON.
While ON is displayed, G output will be on, turning fan on.
Allow up to 10 seconds after button is pressed for fan to turn on
and off. On all 3 through 12.5 ton RTUs the fan continues to
operate for a minimum of 30 seconds after G signal is
removed.
NOTE: In other than the Installer Test mode the fan will run
continuously during the occupied periods. If auto fan is
selected, the fan will come on with a heating or cooling call
during the unoccupied periods and run continuously during the
occupied periods. The fan icon AUTO will be lit if auto fan is
selected and ON will be lit when the fan is on.
TO TEST COOLING AND DEHUMIDIFICATION:
Press MODE button until COOL icon turns on. Y1 cooling
begins within 10 seconds and remains on for 4 minutes. Two
minutes after Y1 comes on, the Y2 signal is energized for
2 minutes. At the end of 4-minute run, cooling stops and
MODE reverts to OFF. At any time during 4-minute run time,
cooling may be turned off by pressing MODE button until
OFF appears. While cooling is on, successive presses of
HUMIDITY button turns the dehumidify output on and off.
While this output is active, the “DEHUM” icon will be
energized.
TO TEST PRIMARY HEATING:
Press MODE button until HEAT icon turns on. W1 heating
begins within 10 seconds and remains on for 4 minutes. This
is the Recycling mode and if the outdoor temperature is below
the balance point it will also include first stage furnace or
electric heat in AC system, and heat pump heating in heat
pump system. W1 will be on for 2 minutes followed by second
stage W2 for 2 minutes. If the outdoor temperature is above the
balance point, this second stage call will energize first stage
furnace or electric heat in AC system and heat pump heating
in heat pump system. If the outdoor temperature is below
the balance point this second stage call will energize second
stage furnace or electric heat in AC system and heat pump
system. At the end of 4-minute run, heating stops, and MODE
reverts back to OFF. At any time during 4-minute run time,
heating may be turned off by pressing MODE button until
OFF appears. While heating is on, successive presses of
HUMIDITY button turn Occupied output on and off. While
this output is active, “OC” appears in cool set point display.