ActronAir Ambient Temperature Sensor monitors ambient air temperature for ActronAir residential split ducted systems, providing the ambient reference data the system PCBs use to set operating limits and manage capacity in high-ambient and low-ambient conditions. Accurate ambient sensing is critical for systems with extended operating range ratings -- a failed ambient sensor causes the system to operate without ambient-based protection limits, risking compressor damage in extreme temperature conditions. Isolate power at mains before replacing any ambient temperature sensors.