The 1/2" x 3 5/16" flat shaft is designed for standard HVAC blower wheel hubs

or the main burner failing to engage when the thermostat calls for heat due to internal coil failure

Direct Cross-Reference: Engineered as a verified replacement for older Johnson Controls assemblies

If the switch trips repeatedly under normal load

Carrier 50DK505989 Motor Channel 321142-301 The 1/2" x 3 5/16"As a technician in the field, you know that a secure Carrier 50DK505989 Motor Channel is the backbone of a reliable blower assembly. This precision engineered OEM HVAC replacement part is critical for maintaining the structural integrity of the motor mount within industrial and commercial AHUs. Constructed from heavy gauge, corrosion resistant steel, this channel is designed to handle the high torque and constant thermal cycling of Carrier, Bryant,