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3-1
T-312
SECTION 3
TROUBLESHOOTING
CAUTION
Do not under any circumstances attempt to service the microprocessor. Should a problem develop
with the microprocessor, replace it.
NOTE
To access LED display on the microprocessor, remove cover
from main control box located in rear of electrical compartment.
Table 3-1. Microprocessor Error Message Definition
ERROR
CODE
STATUS OF
LED DISPLAY
REMEDY
0
1 sec on - 1 sec off
Not Applicable as system is operating normally.
1
1 flash - 5 sec pause
Record error code number, tag and replace the microprocessor.
2
2 flashes - 5 sec pause
Record error code number, tag and replace the microprocessor.
3
3 flashes - 5 sec pause
Record error code number, tag and replace the microprocessor.
4
4 flashes - 5 sec pause
Record error code number, tag and replace the microprocessor.
5
5 flashes - 5 sec pause
Record error code number, tag and replace the microprocessor.
6
6 flashes - 5 sec pause
Record error code number, tag and replace the microprocessor.
Table 3-2. Display Error Message Definition
ERROR
CODE
MESSAGE
MESSAGE DEFINITION
Er4
Communications Failure
If the display does not receive data from the microprocessor.
Er5
Data Memory
If memory on the display is not verified on power up.
Er6
Program Memory
If program memory on the display is not verified on power up by a checksum.
Table 3-3. Driver Display Panel Alarm Message Definition
ALARM
NO.
TITLE
CAUSE
REMEDY
MICROPROCESSOR RESPONSE
A11
Main Left
Probe Failure
Sensor is unplugged,
wiring defective or
main left evaporator
return air temperature
sensor failure.
Ensure sensor is
plugged in. Check
sensor resistance or
wiring. Replace sen-
sor or repair wiring.
(Refer to section 4.13
and Table 4-3.)
Switches to the right probe. If both
probes are bad, the microprocessor
will run in the full reheat and evapo-
rator fans will operate on low speed.
The compressor will operate on six
cylinders if pressures permit.
A12
Main Right
Probe
Failure
Sensor is unplugged,
wiring defective or
main right evaporator
return air temperature
sensor failure.
Ensure sensor is
plugged in. Check
sensor resistance or
wiring. Replace sen-
sor or repair wiring.
(Refer to section 4.13
and Table 4-3.)
Switches to the left probe. If both
probes are bad, the microprocessor
will run in the full reheat and evapo-
rator fans will operate on low speed.
The compressor will operate on six
cylinders if pressures permit.