I am going to try to explain why you need to disconnect the fan when thawing a heat pump. again, unless you know what you are doing this is not something to try on your own. with the fan running you are drawing cold air across the coil which is going to of course cooling the hot gas down. it may work for a bit but as the coil defrosts it is going to cool the gas down more and more. and as I said before common sense says a cooler hot gas temp is not going to defrost the coil.
-=> HvacTech2