Vehicle cab temperature control system

In a vehicle cab air temperature control system for a cab having an operator enclosure with a roof and an outwardly exposed air filter means attached to the roof of said operator enclosure, the improvement including, in combination:

• a duct secured within said operator enclosure in close proximity below and in spaced relationship to said roof, thereby providing an insulating chamber containing trapped air between substantially the entire expanse of said roof and said duct, said duct is secured to said air filter means and has an inlet aperture adjacent said air filter means within said enclosure to provide an air passage between said duct and said air filter means, an outlet aperture spaced from said inlet aperture to provide an air passage between said duct and said enclosure and a bleed aperture located between said inlet and said outlet apertures to provide an air passage between said duct and said chamber;
• blower means mounted within said duct for supplying a flow of air from outside said air filter means through said air filter means, said inlet aperture, said duct, into said operator enclosure through said outlet aperture and into said chamber through said bleed aperture;
• and
• temperature control means mounted within said duct between said bleed aperture and said inlet aperture for controlling the temperature of the air flowing from said duct into said operator enclosure and said chamber.