Rheem · Air Handlers
This fault indicates an abnormal detection in the fan motor's AD Offset. The issue is likely with the control board's circuit.
Click steps to track your progress.
Turn off your air handler at the thermostat and its main electrical breaker for 5 minutes, then turn both back on.
Check the electrical breaker for your air handler. If it's tripped, flip it completely off, then firmly back to the 'On' position.
Inspect and replace your air filter if it's dirty or clogged. A clean filter ensures proper airflow.
Look for any flashing lights or error codes on your air handler or thermostat display and check your manual for their meaning.
If the fault persists, it's best to contact a professional HVAC technician, as the issue may involve internal control board circuits.