Carrier 69NT40-561-019, Operation And Service Manual

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T-359 4–6
In order to achieve economy mode, a perishable set point must be selected prior to activation. When economy
mode is active, the evaporator fans will be controlled as follows:
At the start of each cooling or heating cycle, the evaporator fans will run in high speed for three minutes. They will
then be switched to low speed any time the supply air temperature is /- 0.2°C (0.36°F) of the set point and
the return air temperature is less than or equal to the supply air tempe3°C (5.4°F). The fans will continue to
run in low speed for one hour. At the end of the hour, the evaporator fans will switch back to high speed and the
cycle will be repeated. If bulb mode is active, the economy fan activity will be overridden.
4.3.6 Perishable Set Point Temperature Control
With configuration variable CnF26 (Heat Lockout Temperature) set to - 10°C the perishable mode of operation is
active with set points above -10 ° C (+14 °F). With the variable set to - 5°C, the perishable mode is active above -5°C
(+23 ° F ). Refer to Table 4–4 .
When in the perishable mode, the controller maintains the supply air temperature at set point, the SUPPLY indica-
tor light will be illuminated on the display module and the default reading on the display window will be the supply
temperature sensor reading.
When the supply air temperature enters the in-range temperature tolerance (as selected at function code Cd30),
the in-range light will energize.
Figure 4.5 Controller Operation - Perishable Mode
NOTE 1: TEMPERATURE INDICATIONS ARE ABOVE OR BELOW SET POINT.
NOTE 2: ECONOMIZED UNLOADED COOLING OCCURS IF RETURN TEMPERATURE
IS GREATER THAN SET POINT PLUS 1.9
_
C AND IF CAPACITY MODULATION
IS GREATER THAN 70%. IF BOTH CONDITIONS ARE NOT MET, STANDARD
UNLOADED COOLING OCCURS.
RISING
TEMPERATURE
HEATING
AIR CIRCULATION
SET POINT
+0.20
_
C
HEATING
+2.5
_
C
(4.5
_
F)
FALLING
TEMPERATURE
MODULATED
UNLOADED
COOLING
--0.5
_
C
(0.9
_
F)
AIR CIRCULATION
--0.20
_
C
MODULATED
UNLOADED
COOLING