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Table 22 — Operation Status Codes
Restart Procedure —
Before attempting to restart the
machine, check the display for alarm codes to determine the
cause of the shutdown. If the unit, circuit, or compressor stops
more than once as a result of a safety device, determine and
correct the cause before attempting to start the unit again.
After the cause of the shutdown has been corrected, unit
restart may be automatic or manual depending upon the fault.
Diagnostic Codes —
Diagnostic codes are warnings of
abnormal or fault conditions, and may cause either one circuit
or the whole unit to shut down. They are assigned code num-
bers as described below.
Table 23 contains a description of each diagnostic code er-
ror and possible cause. Manual reset is accomplished by mov-
ing the ON/OFF Switch to the OFF position, then back to ON.
The 2-digit LED display is used to display the diagnostic
codes and the alarm light (located next to display) is energized
whenever a diagnostic code is tripped. When a problem is
suspected, always check the display first for diagnostic
information.
NOTE: Codes 53, 54, 57, 58, 61, 62, 65-69, 73, 74, and 77-80
are not used on these units.
CODES 51, 52, 55, 56: COMPRESSOR FAILURE — If con-
trol relay (CR) opens while compressor should be operating,
compressor will stop and microprocessor will energize alarm
light and display a code of 51 , 52 , 55 or 56 (depending on
compressor) when display button is pushed. The compressor
will be locked off; to reset, the ON-OFF switch must be turned
to OFF and then to ON position.
If lead compressor in a refrigerant circuit is shut down, the
other compressor in that circuit will also be shut down and
locked off. Only the error code for the lead compressor will be
displayed.
Code 51 is for compressor 1, and Code 55 is for compressor
2. Codes 52 and 56 are used for compressors 3 and 4, respec-
tively, on size 104 units.
The microprocessor has also been programmed to indicate a
compressor failure if CR switch is closed when compressor is
not supposed to be on.
If a failure occurs, the following are possible causes:
High-Pressure Switch Open
— The high-pressure switch for
each compressor is wired in series with 24-v power that ener-
gizes CR. If high-pressure switch opens during operation, CR
will stop compressor and this will be detected by microproces-
sor through the feedback contacts.
Internal Thermostat
— The internal thermostat in each 06D
compressor is also wired in series with 24-v power that ener-
gizes CR. If thermostat fails or switch opens during operation
of compressor, compressor will shut down and failure is detect-
ed through feedback contacts (size 034 and 038 only).
CR Failure
— If CR fails with large relay either open or
closed, microprocessor will detect this, lock compressor off,
and indicate an error.
Relay Board Failure
— If small 24-v relay on the relay board
fails, microprocessor will detect this through feedback contacts
and indicate an error.
Processor Board Failure
— If hardware that monitors feed-
back switch fails and processor board fails to energize the relay
board relay to ON position, an error may be indicated.
The control does not detect compressor circuit breaker
failures.
Wiring Problem
— A wiring error or a loose wire may cause
the feedback circuit to be broken.
CODE MEANING
0
0 cooling stages active
1
1 cooling stage active
2
2 cooling stages active
3
3 cooling stages active
4
4 cooling stages active
5
5 cooling stages active
6
6 cooling stages active
7
7 cooling stages active
8
8 cooling stages active
20
Initialization mode (Allow 2 minutes
for initialization. To initiate Quick Test,
press the Display button while 20 is displayed.)
21
Temperature Reset in effect
22
Demand Limit in effect
26
Morning Warm-Up in effect
30
Internal failure detected
88
Self-diagnostic mode in effect
IMPORTANT: The microprocessor memory and the dis-
play will be cleared if the power to the microprocessor is
shut off. DO NOT attempt to bypass, short, or modify
the control circuit or electronic boards in any way to cor-
rect a problem. This could result in a hazardous operat-
ing condition.