the present invention relates to a composite flexible hose , preferably for use in automotive air conditioning systems , with improved thermal resistance . the hose consists of an innermost core layer , a friction rubber layer , an intermediate reinforcement layer , and an external cover layer . the innermost layer is a non - plasticized polyamide mixed with a minor portion of polyolefin corresponding to the main rubber constituent of the friction coat layer . the friction coating is formed of a rubber composite of two epdm rubbers at a weight ratio of 50 / 50 and 75 parts by weight of carbon black . the intermediate fibrous reinforcement layer is formed of aramid . the external layer is an acrylate rubber comprising a blend of two ethylene acrylates at a weight ratio of 50 / 50 and 80 parts by weight of carbon black .