Abstract: A heater or air conditioning unit is able to efficiently deliver air at a low noise level. The unit is manufactured in accordance with the "component sharing principle," whereby it is provided with an installation space capable of accepting an evaporator for air conditioning, or air-guide devices. The air-guide devices route the incoming air flow without inducing turbulence.

Abstract: A heater and/or air conditioner with air-side temperature adjustment includes adjustment with an air-mix flap in front of a mixing chamber, which with a simple and compact construction, guarantees a clear separation between intake-side fresh-air conduction, on the one hand, and warm air conduction, on the other hand, and exhibits only a small air-side contact resistance. A ring-shaped heat exchanger which is closed upon itself, is provided with a ring-shaped surrounding warm-air-duct disk and an axially upstream, ring-shaped surrounding cold-air-duct disk in each case on the outlet side with a crossover branching off into a shared mixing chamber controllable by an air-mix flap with a connected floor air duct or defrost air duct.