ActronAir Return Air Temperature Sensor monitors return air temperature at the indoor unit on AIRES and Advance R32 residential split ducted systems, providing the return air data the indoor PCB uses to calculate system load, manage capacity, and set operating limits across the connected zone network. An inaccurate return air sensor causes the system to misjudge actual room temperature demand, resulting in comfort complaints that do not correlate with wall controller set points. Isolate power at mains before replacing any temperature sensing components.