An evaporator and a heater may be accommodated in a case. A tunnel in a tubular shape forms a tunnel passage. The case may form an evaporator passage and a heater passage. The evaporator passage may be located on a downstream side of the evaporator and extended without passing through the heater. The heater passage may be located on a downstream side of the heater. The tunnel may extend from the heater passage through the evaporator passage toward an inner wall of the case.