2505-139 Outdoor Axial Fan W3G800-OU23-05 drives condenser airflow across the outdoor coil on commercial package and split ducted systems (PCG, SCA, and Hercules series), rejecting heat from the refrigerant circuit to maintain rated cooling and heating capacity at all operating conditions. This assembly uses a 3-phase EC variable-speed motor (S3G710AU0101) providing electronically controlled airflow modulation via 0-10V signal from the outdoor PCB -- when the outdoor fan fails, condensing pressure rises rapidly in high-ambient conditions, triggering high-pressure protection and compressor lockout within minutes. Isolate power at mains before replacement -- EC motors and 3-phase components retain dangerous residual voltages after power isolation.