It　has　been　known　that　for　space　heating　ASHPs,　their　different　configurations　and　operation　may　influ-ence　their　frosting　performances.　However,　there　has　been　no　comprehensive　coefficient　that　can　be　con-veniently　and　comprehensively　used　to　characterize　the　frosting　status,　severeness　level　of　frosting,　and　the　potential　for　frosting　suppression　during　the　real-time　operation　of　an　ASHP　unit.　Therefore,　in　this　paper,　a　novel　coefficient　of　frosting　suppression　based　on　the　operating　characteristic　for　ASHPs　has　been　proposed,　and　its　development　is　reported.　Firstly,　a　novel　dimensionless　coefficient,　COFS,　to　reflect　the　severeness　of　frosting　for　ASHPs　was　defined.　Secondly,　an　experimental　setup　with　four　variable　speed　experimental　ASHP　units　and　test　conditions　are　described.　Thirdly,　using　the　experimental　results,　COFS-　based　frosting　suppression　performance　maps　for　the　four　units　were　developed.　It　is　shown　that　because　the　experimental　four　units　had　different　frosting　suppression　abilities,　their　frosting　areas　in　their　frost-ing　maps　were　50%,　100%,　94%,　and　58%,　respectively.　In　addition,　as　the　test　conditions　changed,　the　frosting　area　on　a　map　area　could　also　change.　These　have　proved　that　the　proposed　COFS　could　effec-tively　reflect　the　frosting　status　and　the　relative　level　of　frosting　suppression　performances　of　ASHP　in　actual　operation.(c)　2023　Elsevier　B.V.　All　rights　reserved.