Sequence of Operation
OAU-SVX006E-EN 87
Sensor Source Failures
The following diagnostics are displayed when the
respective sensor reading is outside of the expected
range, indicating that the sensor may be faulty. Refer to the
points list for expected ranges of each input.
In some cases, a BAS point is In Service, and will take
p
riority over a hardwired input. If the point was
inadvertently put In Service, and the BAS is either not
writing a value or the value is outside of the expected
range, then the program will first attempt to fall back to a
hardwired input before displaying a source failure
diagnostic.
• Diagnostic: Dehumidification Temperature Sensor
So
urce Failure*
• Diagnostic: Discharge Air Humidity Source Failure
• Diagnostic: Discharge Air Tem
perature Source Failure
• Diagnostic: Duct Static Pressure Source Failure
• Diagnostic: Outdoor Air Flow Sensor Source Failure
• Diagnostic: Outdoor Air Humidity Source Failure
• Diagnostic: Outdoor Air Temperature Source Failure
• Diagnostic: Return Duct/Space
Pressure Source Failure
• Diagnostic: Space CO2 Source Failure
• Diagnostic: Space Humidity Source Failure
• Diagnostic: Space Temperature Source Failure
*The Dehumidification Temper
ature Sensor is the Indoor
Coil Leaving Air Temperature Local on all cabinets except
for the OANG (OAN Rev. 6). For the OANG cabinet, the
sensor is the Discharge Air Humidity Local.
Economizer Fault Detection and
Diagnostics
Not Economizing When It Should be Economizing is
displayed when unit is in Economizer Mode and the
Outdoor Air Damper Position Status Local is 20% below
the Outdoor Air Damper Position Command for 20-
minutes.
Damper Not Modulating i
s displayed if the Outdoor Air
Damper Position Status Local is 20% below the Outdoor
Air Damper Position Command for 20-minutes.
Mixed Air Low Limit Active is displa
yed when the unit
is in Economizer Mode and the unit is limiting the Outdoor
Air Damper Position Command to prevent the mixed air
temperature from falling below 35°F. Units equipped with
Class 1A dampers will use a sensor, Mixed Air
Temperature Local. Otherwise, the unit will estimate the
mixed air temperature using Outdoor Air Temperature
Active, Return Air Temperature Local, and the Outdoor Air
Damper Position Command.
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