Perishable Economy; Perishable Mode Cooling - Sequence Of Operation; Figure 4.6 Perishable Mode Cooling - Carrier PrimeLINE 69NT40-561-200 Operation And Service Manual

4.3.10

Perishable Economy

Economy Fan mode is an extension of the Perishable mode, and is provided for power saving purposes. Economy
Fan mode is activated when Cd34 (also used for Frozen Economy mode) is set to "ON." Economy Fan mode is
used in the transportation of temperature-tolerant cargo or non-respiration items which do not require high airflow
for removing respiration heat.
There is no active display that indicates that Economy Fan mode has been initiated. To check for Economy Fan
mode, perform a manual display of Cd34.
In order to initiate Economy Fan mode, a perishable setpoint must be selected prior to activation. When Economy
Fan mode is active, the evaporator fans will be controlled as follows:
a. At the start of each cooling or heating cycle, the evaporator fans will run in high speed for three minutes.
b. They will then be switched to low speed any time the supply air temperature is within +/- 0.2°C (0.36°F) of
the setpoint and the return air temperature is less than or equal to the supply air temperature + 3°C (5.4°F).
c. The fans will continue to run in low speed for one hour.
d. 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, Economy Fan mode will be overridden.
4.3.11

Perishable Mode Cooling - Sequence of Operation

In Standard Perishable mode, the evaporator motors run in high speed. In Economy Fan mode, the
fan speed is varied.
a. When supply air temperature is above setpoint and decreasing, the unit will cool with the condenser fan
motor (CF), compressor motor (CH), and evaporator fan motors (EF) energized, and the white COOL light
illuminated. (See Figure
tacts TS to open the economizer solenoid valve (ESV) and place the unit in economized operation.
b. When supply air temperature decreases to a predetermined tolerance above setpoint (Cd30), the green IN
RANGE light is illuminated.
c. As air temperature continues to fall, unloaded cooling starts (DUV pulses opens) as the supply air tempera-
ture approaches setpoint. (See
NOTE
4.6). Also, if current or pressure limiting is not active, the controller will close con-

Figure 4.6 Perishable Mode Cooling

ENERGIZED
DE-ENERGIZED
F
HPS
IP-CM
IP-EM1 IP-EM2
HTT
ESV
TS
Figure 4.5).
4–7
ST
24 VOLT POWER
TC CH
CF
TN
EF
TV
ES
TE EF
TH
HR
T-362