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28 Direct-Fired Indoor and Outdoor Units • MUA-SVP01A-EN
Diagnostics
SOLUTION: If burner was not operating prior to shutdown (check prior
alarm log)
1. Is there a prior alarm such as Safety Ckt., Airflow Sw., or Flame Failure?
– Yes. See the Diagnostic section for the previous alarm.
– No. Continue.
2. Is the room air (Room Temp) displayed on the BACview remote, reading
150°F or more?
– Yes. The sensor circuit or the sensor itself is shorted. Unplug the input
jack from the AdaptAire controller. Did the display change to -40°F or less?
– No. There is a short in the controller input. Replace the controller.
– Yes. Disconnect the sensor wiring at the sensor. Connect an ohmmeter
to the sensor. If it is shorted replace the sensor. At 70°F the resistance
should be 10K?. See thermistor output curve for other temperatures. If
it is not shorted, there is a short in the wiring between the sensor and
the input plug. Determine cause and rectify. Refer to Appendix II for a
typical 10K? thermistor output curve.
– No. Continue.
3. Is the discharge air temperature (DA Tempt), displayed on the BACview
remote, reading -40°F or less?
– Yes. The discharge air temperature sensor circuit or the sensor itself is
open. Jumper the input for the sensor. Did the display change to 150°F or
more?
– No. There is an open in the controller input. Replace the controller.
– Yes. Disconnect the discharge air temperature sensor wiring at the
sensor. Connect an ohmmeter to the sensor. If it is open replace the
sensor. At 70°F the resistance should be 10K?. See thermistor output
curve for other temperatures. If it is not open, there is a break in the
wiring between the sensor and the input plug. Determine cause and
rectify.
– No. Continue
4. Reset the alarm. Check and note the DC voltage at controller's analog output
for the heating signal. Set the Heating Setpoint for 90°F. Set the HTG MAX DA
and HTG MIN DA Setpoints for 130°F. Did the Burner VDC, displayed on the
BACview remote, increase?
– No. Unless the outside air temperature is extremely warm the Burner VDC
should have increased to 7.5VDC or more. Close the manual main gas
valve closest to the burner and measure the discharge air temperature. Is
it less than 130°F?
– Yes. There is a problem with the controller program or controller itself.
Contact the factory.
– No. The outside air temperature is too hot to determine the actual
cause of the problem. Reset the alarm and recheck when the outside air
temperature is much cooler.