2-4
Operating Modes
Unit Description
CSR-20 & CSR-40, September 1999
Frozen Loads: Controller Setpoint at -10 C (14 F) or
Below
Temperature control by the controller is based on the return air
sensor temperature. The evaporator fans operate on low speed
(when container return air sensor temperature drops below -10
C [14 F]).
• Cool
• Null (compressor stops, evaporator fans operate, if con-
denser fan is ON, it will operate for 30 seconds and then
stop)
• Defrost (resistance heaters on, evaporator fans stop)
NOTE: If the Economy Mode is set to ON in the
Program menu of the
µµ
P-D controller, the unit
continues in Cool until the return air temperature
decreases to the ECMIN temperature. The
default ECMIN setting is 2.0 C (3.6 F) below set-
point. After the unit shifts to Null, the evaporator
fans stop. During Economy Mode operation, a
Null state timer automatically starts and operates
the evaporator fans on low speed for 5 minutes
every 45 minutes. The unit remains in Null until
the return air temperature increases to ECMAX
temperature at the expiration of a 45 minute Null
state time sequence. The default ECMAX setting
is 1.0 C (1.8 F) above setpoint.
