A zonal climate control system for a vehicle passenger compartment provides independent outside air mixing for zones behind the operator area. A forward zone climate unit comprises, an air circulation system having an outlet to the vehicle passenger compartment, an inlet from the vehicle passenger compartment, an inlet communicating with an outside environment, a heater core coupled to the engine driven heat source and an evaporator coupled to the engine driven air conditioning compressor. The passenger compartment further includes a rearward zone climate unit, comprising, an air circulation system having an outlet to the vehicle passenger compartment, an inlet from the vehicle passenger compartment, an inlet communicating with the outside environment through the exterior skin of the vehicle, a heater core coupled to the engine driven heat source and an evaporator coupled to the engine driven compressor. An actuable door provides for closing and opening the inlet of the rearward zone climate unit communicating with the outside environment. Positioning of the door is under the control of a temperature sensor for the rearward zone. A pressure sensitive check valve is positioned in the inlet of the rearward zone climate unit from the passenger compartment.