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112 SCXG-SVX01B-EN
Diagnostic
Troubleshooting
Diagnostics
Refer to the
IntelliPak
®
Self-Contained
Programming Guide, PKG-SVP01B-EN,
for specific unit programming and
troubleshooting information. In particular,
reference the “Service Mode Menu” and
“Diagnostic Menu” sections in the
programming guide. Refer to the
following text for general diagnostic and
troubleshooting procedures. Common
diagnostics and troubleshooting
procedures follow below.
A
Auto Reset S/A Static Pressure Limit
Problem: The supply air static pressure
went too high.
Reason for Diagnostic: The S/A static
pressure exceeded the S/A static
pressure limit setpoint for at least one
second continuously.
UCM’s Reaction: A "supply air pressure
shutdown" signal is sent to the following
functions:
a. Compressor staging control,
b. Economizer actuator control,
c. Heat operation,
d. Supply fan control,
e. IGV/VFD control,
f. Exhaust fan control,
g. Exhaust actuator control
Reset Required: (PAR) An automatic reset
occurs after the IGV close. The supply fan
is not allowed to restart for 15 seconds
after the diagnostic occurs. An auto reset
will also occur if the unit cycles out of
occupied mode and back.
C
CO
2
Sensor Failure
Problem: The VCM CO
2
sensor input
signal is out of range.
Check: Check field/unit wiring between
sensor and VCM.
Reason for Diagnostic: The unit is reading
a signal that is out of range for the CO
2
sensor transducer input.
UCM’s Reaction: The CO
2
reset function
disables.
Diagnostics
Reset Required: (PAR) An automatic reset
occurs after the CO
2
sensor transducer
input receives a signal that is within range
for ten continuous seconds.
Compressor Contactor Fail - Circuit 1, 2,
3, or 4
Problem: The compressor contactor for
Ckt. 1, 2, 3, or 4 has malfunctioned.
Reason for Diagnostic: The circuit
compressor proving input is detected
closed continuously for more than three
seconds while neither compressor output
on that circuit closes.
UCM’s Reaction: A "lockout ckt #1, 2, 3, or
4 request is issued to the compressor
staging control function.
Reset Required: (PMR) A manual reset is
required after the disgnostic is set. It can
be reset by the HI, Tracer Summit
®
, or by
cycling power to the RTM.
Compressor Trip - Ckt 1, 2, 3, or 4
Problem: The compressor ckt #1, 2, 3, or 4
has tripped.
Reason for Diagnostic: The ckt #1, 2, 3, or
4 compressor proving input is detected
open continuously for more than 3
seconds when either or both compressor
outputs on that circuit energize (as
described in the compressor protection
function).
Reason for Diagnostic: The circuit
compressor proving input is detected
open continuously for more than 3
seconds when either or both compressor
outputs on that circuit energize (as
described in the compressor protection
function).
UCM’ Reaction: A “lockout ckt #1, 2, 3, or
4” request is issued to the compressor
staging control function.
Reset Required: (PMR) A manual reset is
required after this diagnostic occurs. The
diagnostic can be reset by the unit
mounted HI module, Tracer Summit
®
, or
by cycling power to the RTM.
Condenser Temp Sensor Failure - Circuit
1, 2, 3, or 4
Problem: The saturated condenser
temperature input is out of range for
circuit #1, 2, 3, or 4.
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, 2, 3, or 4 saturated condenser
temperature sensor. (temp < -55 F or
temp > 209 F).
UCM’s Reaction: A “Lockout Ckt # 1, 2, 3,
or 4” request is issued to the compressor
staging control function.
Reset Required: (PAR) An automatic reset
occurs after the circuit 1, 2, 3, or 4
condenser temp input returns to its
allowable range within 10 seconds.
D
Dirty Filter
Problem: There is a dirty filter.
Reason for Diagnostic: The filter switch
input on the RTM is closed for more than
60 seconds continuously.
UCM’s Reaction: An information only
diagnostic is set.
Reset Required: (INFO) An automatic
reset occurs after the dirty filter input
reopens for 60 continuous seconds.
E
ECEM Communications Failure
Problem: The RTM has lost
communication with the ECEM.
Check: Field/unit wiring between RTM
and ECEM module.
Reason for Diagnostic: The RTM has lost
communication with the ECEM.
UCM’s Reaction: If the unit has the
comparative enthalpy option, the
economizer enable r.e. enthalpy function
will revert to level 2 enthalpy
comparison.