CNT-SVX05A-EN
67
Troubleshooting
Minimum timers
The controller automatically exits the manual test mode after ten hours and
reverts back to normal operation. The outputs are not subject to minimum times
during the test sequence. However, the test sequence only permits one step per
second, which enforces a minimum output time.
Required inputs for unit operation
The following locally wired sensor or communicated inputs are required for each
listed control function. If any one of the sensors does not exist, the controller
operates the control function.
Table 55 — Required sensors
Diagnostics
Three different types of diagnostics are generated by the Tracer
™
AH.540
controller to help you troubleshoot abnormal unit operation.
Table 56 — Diagnostic types
Table 57 — Controller diagnostics
Control function
Sensor(s) required to be
present - wired sensor or
communicated value
Controller operation if
input is not present
Variable air volume
control
Duct static pressure
Discharge air temperature
Diagnostic shutdown
Diagnostic shutdown
Discharge air
temperature control
Discharge air temperature
Diagnostic shutdown
Space temperature
control
Space temperature
Discharge air temperature
Diagnostic shutdown
Diagnostic shutdown
Economizer operation
Outdoor air temperature
Mixed air temperature
Economizer disabled
Economizer disabled
Critical alarm
The controller shuts down the unit to protect the air handling unit and avert
possible damage, or the controller cannot operate until the diagnostic
condition is corrected.
Service required
The controller disables certain sequences of operation only and attempts to
maintain unit operation. For example, if the mixed air temperature sensor fails
or is not wired, the Tracer AH.540 controller disables (does not allow)
economizer operation.
Informational
This type of diagnostic does not affect controller operation.
Diagnostic or Condition
Control type
configuration
Supply
fan
Other outputs
(Enabled = Normal Operation)
Low Temp Detect
(Notes 1, 6)
CV Space temp control
CV Discharge air control
Variable air volume control
Off
Valves
Open
(hydronic)
Valves
Cycled
(steam)
Outdoor air damper
Closed
Face and bypass damper
Face
Exhaust fan
Off
Duct Static Press
High Limit (Note 6)
Variable air volume control
Off
Valves
Closed
Outdoor air damper
Closed
Face and bypass damper
Bypass
Exhaust fan
Off
Unit Shutdown
(Note 6)
CV Space temp control
CV Discharge air control
Variable air volume control
Off
Valves
Closed
Outdoor air damper
Closed
Face and bypass damper
Bypass
Exhaust fan
Off
Low Supply Fan Air Flow
(Note 6)
CV Space temp control
CV Discharge air control
Variable air volume control
Off
Valves
Closed
Outdoor air damper
Closed
Face and bypass damper
Bypass
Exhaust fan
Off
Dirty Filter
(informational)
CV Space temp control
CV Discharge air control
Variable air volume control
Enabled
Valves
Enabled
Outdoor air damper
Enabled
Face and bypass damper
Enabled
Exhaust fan
Enabled