Compressor Alarm Circuit - Carrier 040-420 Installation And Service Manual

Possible causes of failure:
High-Pressure Switch Open - High-pressure switch for
each compressor is wired in series with 24-v power that
energizes compressor control
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.
3 . Wiring Errors - If a wiring error exists causing CPCS,
CR, or feedback switch not to function properly, micro-
processor indicates an error.
4. 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.
5 . 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
60 Hz units; standard on 070, 50 Hz and 80-l 10 and as-
sociated modular units) will cause a trip.
6. Checkout Procedure - Shut off main power to unit. Turn
then step through subfunc-
on control power,
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:
HPS (high-pressure switch) open
l
Misplaced feedback wire from 54 and J5 terminals
l
points on 53

Compressor Alarm Circuit

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
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,
relay. If high-pressure switch
on 040-060 and 070,
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 Compressor A 1 discharge pressure
transducer failure
Code 23 Compressor B 1 discharge pressure
transducer failure
Code 24 Compressor A 1 suction pressure transducer
failure
Code 25 Compressor B 1 suction pressure transducer
failure
Code 26 Compressor Al oil pressure transducer failure
Code 27 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
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
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.
within o n e minute after