Situation: The indoor fan operates with no call (randomly). 

Technical Information:

The dissipation board software includes a calibration feature designed to ensure the A2L refrigerant sensor receives sufficient fresh air for accurate calibration. This requirement is met if the indoor fan operates continuously for at least 15 minutes during any system call (heating, cooling, or continuous fan mode). If the indoor blower does not achieve a minimum of 15 continuous minutes of operation within a one-week period, the dissipation board will automatically initiate a 15-minute fan cycle to perform the necessary calibration. This process is standard and may occur more frequently during transitional (shoulder) seasons. The procedure applies to all 454B installations, regardless of whether the system is communicating or non-communicating. During the calibration cycle, if a heating or cooling demand is received, the system will allow the requested operation, and the fan will continue running until either the 15-minute calibration period concludes or the demand is satisfied. No fault code or message will be displayed to indicate that the system is in calibration mode. However, if the fan operates without a call due to a dissipation event, the diagnostic light on the dissipation board will flash the active dissipation code. In the event of a sensor error or other fault, the blower will run continuously and display the corresponding fault code. For communicating systems, dissipation events and fault codes will be shown on the wall control interface.