Abstract: A rotary temperature mechanism for controlling the temperature door of a HVAC system of a vehicle includes a rotatable cam connected by a shaft to a rotary temperature control knob. The cam includes a helical rib thereon coacting with a carrier restricted to linear, sliding motion by the housing in response to rotation of the cam. The housing provides a linear track for guiding the carrier. Detent members are provided between the cam and housing to impart discrete stepping feel on rotation of the knob. The detent members include ball bearings on the cam rolling along a corrugated track of the housing. A cable is connected to the carrier and controls the temperature door by linear motion imparted thereon.