Carrier SUPRA 950Mt - Introduction; Microprocessor Configuration; Before Starting the Unit

62-11863 3-2
3.1.1 Introduction
The microprocessor and relay module is housed in the control box:
• The processor board includes the microprocessor, program memory, and necessary input/output circuitry to
interface with the unit.
• The relay module contains replaceable relays and fuses along with the wiring harness.
The cab command is mounted remotely in the truck, and includes the LCD display, keypad, and keypad interface
(See Figure 3.1).
The microprocessor provides the following features:
• Controls return air temperature by providing refrigeration control, heat, and defrost to ensure conditioned air
delivery to the load.
• Independent readouts of set point and return air temperatures.
• Digital readout and ability to select unit operational data. Refer to Table 3–1 for function codes, Table 3–6
for unit data codes, and Table 3–7 for alarm digital display identification.
• A self-test check on program memory and data memory. The self-test is executed each time the system is
switched from OFF to ON. Errors, if any, are indicated on the display as a ERR.X, where X is a number cor-
responding to the number of the test. The unit displays this error for five seconds and then resets the micro-
processor.
3.2 MICROPROCESSOR CONFIGURATION
The microprocessor is configured in accordance with the equipment supplied on an individual unit and the require-
ments of the original purchase order. The configurations do not require change unless the unit has an equipment
change or a change is required by the owner.
Although the configurations may not be modified using the keypad, operational differences are noted throughout the
following descriptions and operating procedures.
Some microprocessor settings such as set point and functional parameters can be changed at the keypad, and are
described in the following sections.
3.3 BEFORE STARTING THE UNIT
Prior to starting the unit, the I/O switch should be in the RUN (I) position and the RUN/STOP switch, which is
located on the side of the electrical box, should be in the RUN position.
The microprocessor will power up and go through a self test. It will then show OFF in the display.
Error Cause
ERR.1, ERR.2, ERR.3 Processor failure
Check chip installation or replace microprocessor
ERR.4 Display board to logic board communication failure.
This can be caused by a defective ribbon cable or ribbon cable not
ERR.5 Processor RAM test failure at micro start up. Replace microprocessor.
ERR.6 Processor ROM test failure at micro start up. Replace microprocessor.