SCXF-SVX01T-EN
97
Category Diagnostic
Check
If have an external sensor connected to the NSB panel zone sensor input, then the internal NSB panel zone sensor should be disabled. Verify
sensor resistance. If in valid range, check wiring between the sensor and NSB panel.
NSB Panel Comm Failure
Problem
The RTM has lost communications with the night setback panel (programmable zone sensor).
Check
Field/unit wiring between RTM and NSB Panel.
Reason for
Diagnostic
The RTM has lost communication with the NSB panel.
Controls
Reaction
The unit reverts to the next lower priority mode switching source (typically the HI default mode). If the NSB panel zone sensor is the designated
sensor source for any functions, those functions are disabled.
Reset
Required
(PAR) An automatic reset occurs after communication has been restored.
O
O/A Humidity Sensor Failure
Problem
The outside air humidity sensor data is out of range.
Check
Check field/unit wiring between the sensor and RTM.
Reason for
Diagnostic
The unit is reading a signal that is out of range for the outside air humidity sensor (humidity < 5% or humidity > 100%).
Controls
Reaction
The economizer enable enthalpy function reverts to dry-bulb temperature changeover (“Level 1”) control.
Reset
Required
(PAR) An automatic reset occurs after the OA humidity input returns to its allowable range for 10 seconds.
O/A Temp. Sensor Failure
Problem
The outside air temperature sensor input is out of range.
Check
Sensor resistance should be between 830 ohms (200°F) and 345.7 ohms (-40°F). If so, check field/unit wiring between sensor and RTM.
Reason for
Diagnostic
The unit is reading a signal that is out of range for the outside air temperature input on the RTM (temp. < -55°F or temp > 209°F).
Controls
Reaction
These unit functions occur:
• Low Ambient Compressor Lockout Disables
• O/A damper drives to minimum position
• On VAV units with S/A temp. reset type selected as O/A temp. reset, the reset type reverts to “none” for the duration of the failure
Reset
Required
(PAR) an automatic reset occurs after the O/A temperature input returns to its allowable range. To prevent rapid cycling of the diagnostic, there
is a 10 second delay before the automatic reset.
Occupied Zone Heat Setpoint Failure
Problem
The occupied zone heat setpoint input is out of range.
Reason for
Diagnostic
The input designated as occupied zone heating setpoint source is out of range for the outside air temperature input on the RTM (temp. < 45°F
or temp > 94°F).
Reaction
The active occupied zone heating setpoint reverts to the default value.
Reset
Required
(PAR) an automatic reset occurs after the occupied zone heating setpoint input returns to its allowable range for 10 continuous seconds, or
after a different occupied zone heating setpoint selection source is user-defined.
R
Return Air Humidity Sensor Failure
Problem
On units with both airside economizer and comparative enthalpy installed, the return air humidity sensor input is out of range.
Check
Check field/unit wiring between the sensor and ECEM.
Diagnostics
To Next Page
Loading...