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3-2
3.2.2
Microprocessor Module
The microprocessor controls the following functions:
a. Maintains the box temperature at setpoint by regulating the cooling, heating, off mode and automatic defrost cycles.
b. Permanently displays the return air temperature and, on request, the setpoint temperature.
c. Digital display and selection of data.
For further details on digital message display, see
.
3.2.3
Cab Command
The Cab Command is mounted in the cab and allows the driver to carry out the control operations listed below:
• Manual start-up and shut-down of the unit
• Automatic start-up of the unit
• Adjusting the setpoint
• Initiating manual defrost
As soon as setpoint temperature has been reached, temperature control is obtained by shut-down and start-up of
the electro-magnetic clutch. The condenser and evaporator fans cut out at setpoint. When transporting fragile
loads such as fresh meat, vegetables and cheese, it is possible to program the microprocessor to obtain continu-
ous ventilation by the evaporator while at setpoint.
The driver can display the box temperature, and see whether the setpoint is being maintained by checking the
green indicator. The indicator lights up red in the event of a malfunction.
When the battery voltage is too low, a fail-safe system shuts down the unit. Unit restart is automatic and time-
delayed if the voltage rises to the normal level.
Figure 3.1 Cab Command
a. Display
The digital display consists of 3 alphanumeric characters. The default value displayed is the box temperature. The micro-
processor enables display of the temperature in either Celsius or Fahrenheit, dependent on jumper position (See
). The display also includes settings for defrost operation (dF). The display includes three LEDs described below:
Indicates that the unit is running and whether temperature
is displayed in Celsius or Fahrenheit.
Digital Display (3 digits)
Unit operating LED - GREEN
Indicates the 3 different modes:
ON
: Cooling Mode
OFF
: Null Mode (regulation)
Flashing
: Heating Mode
Alarm LED - RED
Flashes in case of a malfunction.