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SCXG-SVX01B-EN 113
Diagnostic
Troubleshooting Diagnostics
Reset Required: (PAR) An automatic reset
occurs after communication has been
restored.
Emergency Stop
Problem: The emergency top input is
open.
Reason for Diagnostic: An open circuit
has occurred on the emergency stop
input caused either by a high duct temp t-
stat trip, or the opening of field-provided
contacts, switch, etc.
UCM’s Reaction: Off or close requests are
issued as appropriate to the following
functions;
a. Compressor staging/chilled water
cooling control
b. Heat operation
c. Supply fan control and proof of
operation
d. Exhaust fan control and proof of
operation.
e. Exhaust actuator control
f. Outside air damper control
g. On VAV units, IGV/VFD control
Reset Required: (PMR) A manual reset is
required after the emergency stop input
recloses. The diagnostic can be reset by
the HI, Tracer Summit
®
, or by cycling
power to the RTM.
Entering Cond Water Temp Sensor Fail
Problem:
Activation Conditions: temperature < -50
F or temperature > 209 F, and unit
configured for water cooled
condenser
c. Time to React: 10 sec < T < 20 sec
d. Diagnostic Text (Human Interface
Display) “ENT COND WATER TEMP
SENSOR FAIL”
e. Actions to be Initiated: A “Lockout All
Ckts ” request is issued to the
“Compressor Staging Function”
f. Reset: An automatic reset occurs after
the entering condenser water
temperature input returns to within range
continuously for 15 seconds.
Entering Water Temp Sensor Fail
a. Data used (module,packet,byte,bit):
WSM, 01,18,05
b. Activation Conditions: temperature < -
50 F or temperature > 209 F, and unit
configured with water cooled
condenser and/or economizer
c. Time to React: 10 sec < T < 20 sec
d. Diagnostic Text (Human Interface
Display) “ENTERING WATER TEMP
SENSOR FAIL”
e. Actions to be Initiated: A “Disable
Water Side Economizer” request is
issued to “Water Side Economizer
Temperature Enable Function”
f. Reset: An automatic reset occurs after
the Entering Water Temp. input returns to
within range continuously for 10 seconds.
Evap Temp Sensor Failure - Circuit 1, 2, 3,
or 4
Problem: The evaporator temperature
sensor (ckt #1, 2, 3, or 4) is out of range.
Check: Sensor resistance should be
between 830 ohms (200 F) and
345.7Kohms (-40 F). If so, check field/unit
wiring between sensor and MCM/SCM.
Reason for Diagnostic: The unit is reading
a signal that is out of range for the circuit
#1 evaporator temperature sensor input
(temp < -55 F or temp > 209 F).
UCM’s Reaction: The coil frost protection
function for the refrigeration circuit (#1,
2,3, or 4) only is disabled.
Reset Required: (PAR) An automatic reset
occurs after the #1, 2, 3, or 4 evap temp
input returns to its allowable range for 10
seconds.
G
GBAS 0-5 VDC Module Comm Failure
Problem: The RTM has lost
communication with the GBAS module.
Check: Field/unit wiring between RTM
and GBAS.
Reason for Diagnostic: The RTM has lost
communication with the GBAS module.
UCM’s Reaction: The UCM will initiate the
following actions;
a. If the demand limit input was closed
prior to the communications loss, then
the demand limit commands issued to
the heat operation function (if
applicable) and the compressor staging/
chilled water cooling function will be
cancelled.
b. If any of the GBAS setpoint control
parameters are the HI-selected setpoint
sources, then those setpoints will revert
to the default HI setpoints.
c. Any active GBAS output control
parameters will be ignored.
d. A failsafe function in the GBAS module
will cause all GBAS outputs to be
zeroed and deenergized.
Reset Required: (PAR) An automatic reset
occurs after communication has been
restored.
H
Heat Failure
Problem: The heat has failed.
(Electric heat unit) Typically, this is
because the electric heat section became
too hot.
Reason for Diagnostic: The heat fail input
on the heat module was closed:
a. for more than 80 seconds,
b. for ten consecutive occurrances (each
lasting five seconds or more) within a
210 second period.
UCM’s Reaction: An information only
diagnostic is set.
Reset Required: (INFO) An automatic
reset occurs after the heat fail input
remains open for 210 seconds
continuously.
Heat Module Auxilliary Temperature
Sensor Fail
Problem: The heat mod aux temp sensor
input is out of range.
Check: Sensor resistance should be
between 830 ohms (200 F) and
345.7Kohms (-40 F). If so, check field/unit
wiring between sensor and heat module.
Reason for Diagnostic: At least one
enabled unit function has the heat
module auxillary temperature input
designated as its sensor, and the unit is
reading a signal that is out of range for