68
CNT-SVX05A-EN
Troubleshooting
Table 56 – (continued) Controller diagnostics
Note 1:
If the low temp detect device requires manual reset, reset the freezestat device first before resetting the
controller.
Note 2:
When a local temperature, setpoint, or pressure sensor has failed after being valid, the controller generates a
diagnostic to indicate the sensor loss condition. The controller automatically clears the diagnostic once a valid sensor
value is present (non-latching diagnostic).
Note 3:
If the local outdoor air temperature sensor fails and a communicated value is not present, the outdoor air
damper is opened to minimum position and economizer operation is disabled.
Note 4:
If the air handling unit's mixed air sensor fails or is not present, economizer operation is disabled and the
outdoor air damper is opened to minimum position.
Note 5:
A space temperature failure diagnostic disables morning and daytime warm-up sequence of operation when
the controller is configured for constant volume discharge air control or variable air volume control.
Note 6:
This diagnostic message can be configured as a service required or critical alarm.
Diagnostic or Condition
Control type
configuration
Supply
fan
Other outputs
(Enabled = Normal Operation)
Low Exhaust Fan Air Flow
(service required)
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
Off
Discharge Air Temp Fail-
ure (Notes 2, 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
Space Temperature Fail-
ure
(Notes 2, 6)
CV Space temp control
Off
Valves
Closed
Outdoor air damper
Closed
Face and bypass damper
Bypass
Exhaust fan
Off
Space Temperature Fail-
ure
(service required)
(Notes 2, 5)
CV Discharge air control
Variable air volume control
Enabled
Valves
Enabled
Outdoor air damper
Enabled
Face and bypass damper
Enabled
Exhaust fan
Enabled
Outdoor Air Temp
Failure
(service required)
(Notes 2, 5)
CV Space temp control
CV Discharge air control
Variable air volume control
Enabled
Valves
Enabled
Outdoor air damper
Minimum
position
(Note 3)
Face and bypass damper
Enabled
Exhaust fan
Enabled
Mixed Air Temp Failure
(service required)
(Note 2)
CV Space temp control
CV Discharge air control
Variable air volume control
Enabled
Valves
Enabled
Outdoor air damper
Minimum
position
(Note 4)
Face and bypass damper
Enabled
Exhaust fan
Enabled
Maintenance Required
(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
Local Fan Switch Failure
(informational)
(Note 2)
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
Local Space setpoint Fail-
ure
(service required)
(Note 2)
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
Duct Static Press Failure
(Notes 2, 6)
Variable air volume control
Off
Valves
Closed
Outdoor air damper
Closed
Face and bypass damper
Bypass
Exhaust fan
Off
Duct Static Press Failure
(informational)
(Note 2)
CV Space temp control
CV Discharge air control
Enabled
Valves
Enabled
Outdoor air damper
Enabled
Face and bypass damper
Enabled
Exhaust fan
Enabled
Invalid Unit Configuration
(service required)
(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
Normal
(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