MODGAS-XWR-1 Technical Guide
TROUBLESHOOTING
31
Troubleshooting Alarms
Mechanical Failure:
•
Check relay outputs on the MODGAS-XWR for 24
VAC output.
•
Verify the SAT OPTIONS jumper settings on the
MODGAS-XWR for Supply Air Temperature Sensor.
•
Verify gas valve LED is solid. Try forcing valves (refer
to Force Screens in this guide).
•
Verify that the Supply Air Temperature Sensor is
connected to SAT and GND on the MODGAS-XWR
(stand-alone mode) or to AI2 (VCM-X or VCB-X) or
to AI3 (VCCX2) and GND on the Main Controller
(communicating mode).
•
Verify Supply Air Temperature Sensor probe is
mounted correctly in supply duct.
•
Remove SAT and GND wiring from the MODGAS-
XWR and ohm sensor out (this may indicate open or
failed wiring). Refer to chart on
pages 32-33
of this
guide for readings.
Fail Mode - Supply Air Temperature Sensor
Failure:
•
Verify that the Supply Air Temperature Sensor is
connected to the SAT and GND on the MODGAS-
XWR (stand-alone mode) or to AI2 (VCM-X or
VCB-X) or to AI3 (VCCX2) and GND on the
Main Controller (communicating mode).
•
Remove SAT and GND wiring from MODGAS-XWR
and ohm sensor out (this may indicate open or failed
wiring). Refer to chart on
pages 30-31
of this guide
for readings.
•
Verify the SAT OPTIONS jumper settings on the
MODGAS-XWR for the Supply Air Temperature
Sensor.
Fail Mode - SAT Cutoff:
•
Remove SAT and GND wiring from the MODGAS-
XWR and ohm sensor out (this may indicate open or
failed wiring). Refer to chart on
pages 32-33
of this
guide for readings.
•
With Supply Air Sensor disconnected from the
MODGAS-XWR, set volt meter to DC volts and
measure voltage between SAT and GND on board.
Refer to chart on
page 32
of this guide
for readings.
•
Verify Supply Air Temperature Sensor reading in duct
with 3rd party temperature testing device.
Communications Loss:
•
Check COMM LED on MODGAS-XWR.
•
Verify 24 VAC power to all interconnected AAON
controllers.
•
Verify E-BUS connection between the MODGAS-
XWR and associated AAON controllers.
•
In communication mode (connected to an AAON unit
Controller with modular cable), confi rm that Main
MODGAS screens shows COMM MODE that Main
Controller’s MODGAS status screen displays
MODGAS-XWR’s Position %.
Troubleshooting Alarms
