Installation and Maintenance Manual

Diagnostics
11 6 UNT-SVX07D-EN
Manual (Latching) Diagnostics (UC400). Manual
diagnostics (also referred to as latching) cause the unit to
shut down. Manual diagnostics can be cleared from the
UC400 controller in one of the following ways:
• By using the Tracer TU service tool to reset latching
diagnostics on the Alarms Status tab or by
temporarily overriding the Reset Diagnostic
Request (bv/2) on the Binary Status tab.
• Through a building automation system.
• By cycling power to the controller
. When the 24Vac
power to the controller is cycled OFF and then ON
again, a power-up sequence occurs.
Automatic (Non-latching) Diagnostics (UC400).
Automatic diagnostics clear automatically when the
problem that generated the diagnostic is solved.
Smart Reset Diagnostics (UC400). Smart Reset
Diagnostics are latching diagnostics that will auto-recover
if the condition is corrected. After the controller detects the
first smart reset diagnostic, the unit waits 30 minutes
before initiating the smart reset function. If another
diagnostic of this type occurs again within 24 hours after
an automatic clearing, clear the diagnostic manually by
using any of the ways listed under the preceding section,
“Manual (Latching) Diagnostics (UC400).”
Informational Diagnostics (UC400). Informational
diagnostics provide information about the status of the
controller. They do not affect machine operation, but can
be cleared from the controller using the BAS or Tracer SC.
Table of Diagnostics (UC400)
Tab l e 4 4 lists each diagnostic that can be generated by the
UC400 controller, the diagnostic effect on outputs
(consequences), and diagnostic type.
Note: The generic binary output is unaffected by
diagnostics.
Table 44. UC4000 diagnostics
Diagnostic Probable Cause Consequences
Diagnostic
Type
Filter change
required
Fan run hours
exceed the time set
to indicate filter
change.
•Fan Unaffected
•Valves Unaffected
•Electric heat
Unaffected
Informational
Condensate
overflow
The drain pan is full
of water.
•Fan OFF
•Valves Closed
• Outdoor air damper
Closed
• DX/electric heat OFF
Manual
Low coil
temp
detection
The leaving fluid
temperature may be
close to freezing.
•Fan OFF
•Valves Open
• Outdoor air damper
Closed
• DX/electric heat OFF
Smart reset/
Manual
Low airflow
supply fan
failure
The fan drive belt,
contactor, or motor
has failed.
•Fan OFF
•Valves Closed
• Outdoor air damper
Closed
• DX/electric heat OFF
Manual
Space
temperature
failure
(a)
Invalid or missing
value for zone
temperature.
• Discharge air
temperature control
runs
• Unit shuts OFF if both
space temperature
and discharge air
temperature fail
Automatic
Entering
water temp
failure
Invalid or missing
value for zone
temperature.
•Fan Unaffected
(enabled)
•Valves Unaffected
• Outdoor air damper
Unaffected
•DX/electric heat
Unaffected
Automatic
Discharge air
temp low
limit
Discharge air
temperature has
fallen below the
Discharge Air
Temperature Low
Limit.
•Fan OFF
•Valves Open
• Outdoor air damper
Closed
•DX/electric heat OFF
Smart reset/
manual
Discharge air
temp
failure
(a)
Invalid or missing
value for discharge
air temperature.
• Simplified zone
control algorithm runs
• Unit shuts OFF if zone
temperature fails
Automatic
Outdoor air
temp failure
Invalid or missing
value for outdoor air
temperature.
•Fan Unaffected
•Valved Unaffected
• Outdoor air damper
Minimum
Position
• DX cooling/electric
heat unaffected
Automatic
Humidity
input failure
Invalid or missing
value for relative
humidity.
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper
Unaffected
• DX cooling/electric
heat Unaffected
Automatic
CO
2
sensor
failure
Invalid or missing
value for CO
2
.
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper
Unaffected
• DX cooling/electric
heat Unaffected
Informational
Generic AIP
failure
Invalid or missing
value for generic
analog input.
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper
Unaffected
• DX cooling/electric
heat Unaffected
Informational
Local fan
mode failure
Invalid or missing
fan-speed switch
(reverts to default
fan speed).
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper
Unaffected
• DX cooling/electric
heat Unaffected
Automatic
Local
setpoint
failure
Invalid or missing
value for zone
temperature
setpoint (reverts to
default setpoint).
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper
Unaffected
• DX cooling/electric
heat Unaffected
Automatic
(a) For detailed information about zone temperature control methods, refer
to “Zone Temperature Control (UC400),” p. 100.
Table 44. UC4000 diagnostics (continued)
Diagnostic Probable Cause Consequences
Diagnostic
Type
UNT-SVX07_-EN.book Page 116 Friday, April 27, 2012 9:40 AM