MHGRV-X Field Technical Guide
TROUBLESHOOTING
15
Alarm Troubleshooting
Supply Air Temperature Failure:
•
Verify that the Supply Air Temperature Sensor is
connected to the SAT and GND on the MHGRV-X
or MODGAS Controller (stand-alone mode or when
using a CAV/VAV or MUA Controller) or to AI2
and GND on the Main Controller (communicating
mode).
•
Remove SAT and GND wiring from MHGRV-X
and ohm sensor out (this may indicate open or
failed wiring). Refer to chart in back of this guide
for readings.
•
Verify the SAT OPTIONS jumper settings on the
MHGRV-X for the Supply Air Temperature Sensor.
Troubleshooting
Figure 5: MHGRV-X Controller LED Locations and Descriptions
Communications Loss:
•
Check COMM LED on MHGRV-X.
•
Verify 24 VAC power to all interconnected
AAON controllers.
•
Verify E-BUS connection between the MHGRV-X
and associated AAON controllers.
•
In communication mode (connected to an AAON
Unit Controller with modular cable), confi rm that
Controller’s MHGRV-X status screen displays
MHGRV-X’s Position % and that Main MHG
Reheat screens show COMM MODE.
