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Possible causes of failure:
1.
3
d.
3.
4.
5.
6.
High-Pressure Switch Open
-
High-pressure switch for
each compressor is wired in series with 24-v power that
energizes compressor control relay. If high-pressure switch
opens during operation, compressor stops. This is
detected by microprocessor through the feedback
terminals.
DSIO-LV or DSIO-EXV Module Failure
-
If a DSIO-LV
relay module relay fails open or closed, microprocessor
detects this, locks compressor off and indicates an error.
Wiring Errors
-
If a wiring error exists causing CPCS,
CR, or feedback switch not to function properly, micro-
processor indicates an error.
Processor (PSIO) Failure
-
If hardware that monitors
feedback switch fails, or processor fails to energize re-
lay module relay to on, an error may be indicated.
NOTE: The control does not detect circuit breaker fail-
ures. If a circuit breaker trips on lead compressor in a
circuit, a low oil pressure failure is indicated. On the
other compressors, no failure is indicated.
Ground Fault Module on 130-2 10, 225, 250, 280, and
associated modular units (CGFA or CGFB) Open
-
Mod-
ule contacts are in lead compressor circuits, but ground
fault could be in any compressor in affected circuit.
Ground fault of any 040-l 10 and associated modular unit
compressor (field-supplied accessory on 040-060 and 070,
60 Hz units; standard on 070, 50 Hz and 80-l 10 and as-
sociated modular units) will cause a trip.
Checkout Procedure
-
Shut off main power to unit. Turn
on control power,
then step through subfunc-
tion
MFi
to proper compressor number (i.e., failure
code 5 is compressor
Bl).
Next, energize the step. If
step works correctly, then failure code is caused by:
l
HPS (high-pressure switch) open
l Misplaced feedback wire from
54
and J5 terminals
0
Ground wire and 24-v feeds reversed on one or more
points on
53
Compressor Alarm Circuit
-
For compressor Al
alarm circuit, processor closes contacts between
54
termi-
nals 2 and 3 to start compressor. See Fig.
10A
-
10D. Safe-
ties shown to left of
54
must be closed in order for power to
reach compressor control relay, and the feedback input ter-
minals on J3.
Failure of power to terminal 1 on 53, when contacts be-
tween 2 and 3 on J4 should be closed, causes a code 1
alarm.
Terminal 2 on
53
is the other leg of the compressor Al
feedback channel. It is connected to the 24-v common.
NOTE: Similar connections for each compressor can be
lowed on the unit wiring diagrams located on the unit.
Code 9 Leaving water thermistor failure
Code 10 Entering water thermistor failure
fol-
If temperature measured by these thermistors is outside
range of -40 to 240 F (-40 to 116 C), unit shuts down after
going through a normal
pumpout.
Reset is automatic if tem-
perature returns to the acceptable range, and unit start-up
follows normal sequence. Cause of fault is usually a bad
thermistor, wiring error, or loose connection.
Code 19 Compressor Al suction sensor failure
Code 20 Compressor Bl suction sensor failure
On units with thermistors, if temperature measured by
these thermistors is outside the range of -40 to 240 F (-40
to 116 C), affected circuit shuts down after going through a
normal
pumpout.
Other circuit continues to run. Reset is
automatic if temperature returns to the acceptable range,
and circuit start-up follows normal sequence. Cause of
this-
fault is usually a bad thermistor, wiring error or loose
connection.
On units with transducers, if the saturated suction tem-
perature is greater than the leaving water temperature plus
10” F (5.5 C) for more than 5 minutes, the affected circuit
shuts down (after going through normal pumpout). The re-
set is automatic if the saturated suction temperature returns
to the acceptable range and start-up follows the normal se-
quence. Cause of this fault is usually a bad transducer, a
wiring error, or a loose connection.
Code 21 Reset thermistor failure (applies only to installa-
tions having external temperature reset)
If temperature measured by this thermistor is outside range
of
40
to 240 F (-40 to 116 C), reset function is disabled
and unit controls to normal set point. If temperature returns
to the acceptable range, reset function is automatically en-
abled. Cause of this fault is usually a bad thermistor, wir-
ing error or loose connection.
Code 22
Code 23
Code 24
Code 25
Code 26
Code 27
Compressor A 1 discharge pressure
transducer failure
Compressor B 1 discharge pressure
transducer failure
Compressor A 1 suction pressure transducer
failure
Compressor B 1 suction pressure transducer
failure
Compressor Al oil pressure transducer failure
Compressor Bl oil pressure transducer failure
If output voltage of any of these transducers is greater
than 5 v, affected circuit shuts down without going through
pumpout
process. Other circuit continues to run. Reset is
automatic if output voltage returns to the acceptable range,
and circuit start-up follows normal sequence. Cause of fault
is usually a bad transducer or a wiring error.
Code 28 Low transducer supply voltage
If transducer supply voltage is less than 4.5 v or greater
than 5.5 v, unit shuts down without going through pumpout
process. Reset is automatic if supply voltage returns to the
acceptable range, and circuit start-up follows normal se-
quence. Cause of fault is usually a faulty transformer, or
primary voltage is out of range.
The voltage supplied to the processor is polarized. When
checking for proper voltage supply, be sure to consider this
polarity. If voltage appears to be within acceptable toler-
ance, check to be sure the transformer supplying PSl is not
grounded. Grounding the supply transformer can result in
serious damage to the control system.
Code 29 Chilled water pump interlock switch open
(applies only if unit is configured for use with
a chilled water pump interlock).
Code can occur under any of these conditions:
1. Interlock switch fails to close
chilled water pump starts
within
one
minute after
2. Interlock switch opens during unit operation
3. Interlock voltage is detected, but unit is not configured
for interlock
4. Interlock voltage is outside its valid range
If any of these conditions occur, all compressors are dis-
abled and, if running, shutdown occurs without
pumpout.
Chilled water pump also shuts down. Reset is manual, with
LOCAL/ENABLE-STOP-CCN switch. Most probable cause
of this fault is shutdown or failure of chilled water pump to
start. Other possibilities are improper configuration or wir-
ing errors.
50