The　frost-free　refrigerator　typically　has　three　compartments,　i.e.　refrigerating,　variable-temperature　and　freezing　ones.　The　temperature　and　humidity　(T&H)　inside　each　compartment　vary　dramatically,　leading　to　non-uniform　T&H　distribution　in　the　overall　return　air.　Therefore,　frost　maldistribution　occurs　on　the　evaporator　and　further　induces　airflow　redistribution.　In　this　article,　the　quasi-static　3–2–1–1　frosting　model　is　built　considering　3D　evaporator,　2D　T&H　of　frontal　airflow,　1D　frost　growth　and　1D　non-uniform　fin　spacing.　The　model　is　verified　by　the　experiment　data　in　the　open　literature.　Results　show　that　frost　mass　is　similar　with　non-uniform　and　uniform　T&H　distribution　in　frontal　airflow,　but　frost　distribution　is　much　different.　The　evaporator　capacity　for　non-uniform　airflow　is　lower　at　the　early　stage　of　frosting　process　than　that　for　uniform　airflow,　but　higher　later　due　to　the　airflow　transverse　redistribution　when　the　airflow　transfers　transversally　from　higher　to　lower　T&H　areas　owing　to　frost　maldistribution.　The　transverse　redistribution　results　in　the　air　velocity　increment　and　heat　transfer　compensation　effect.　Moreover,　the　fan　stall　for　non-uniform　airflow　arises　later　and　results　in　the　larger　airflow　rate　and　evaporator　capacity　at　later　frosting　process.　©　2020