Typically, most modern air conditioning units can last between 15 to 20 years, and most furnaces can work properly for 15 to 30 years. http://www2K.biglobe.NE.Jp/~kao-nori/jawanote.cgi?js=eyjhbgcioijiuzi1niisinr5cci6ikpxvcj9.eyjhdwqioijkb2tlbiisimv4cci6mtyzntm0mza0niwiawf0ijoxnjm1mzm1odq2lcjpc3mioijkb2tlbiisimpzijoxlcjqdgkioiiycw91mmljdgjkzghzmmrpcjgxbjm2a2iilcjuymyioje2mzuzmzu4ndysinrzijoxnjm1mzm1odq2mdawotgwfq.qbosua9ilpw_jpkrxavx2nrj2ssbzmp_caqvh7croqs&page=0&sid=0c37d22a-371d-11ec-8074-f31464f85302&url=Www2K.Biglobe.Ne.jp/~kao-nori/jawanote.cgi%3Fjs%3Deyjhbgcioijiuzi1niisinr5cci6ikpxvcj9.eyjhdwqioijkb2tlbiisimv4cci6mtyzntm0