Hotpoint fridge freezer model ff71p fridge keeps dropping temperature freezer ok

This more than likely is because your evap.coil is frosted up do to a part failure with the defrost system. Look at the freezer back panel is there alot of frost growing all over it this is the number one sign. Either way take the back panel off and make a visual check. If there is alot of frost first get a multimeter and set it on Ohms with alert chime meaning you get continuity. First check the defrost heat if you get the chime sound from the meter or NOT a infinite number of Ohms then its good. Then look for the round shaped part hooked to the evap and in series to the heater this is the bimetal (while its good and cold) cut wires to it and strip ends and check for continuinty there also if so, it's good but must be frozen cold to get continuity wire nut it back after check if good. If those parts check out then your mechanical defrost timer is bad or adaptive defrost board is bad it would be either one depending on this model of fridge you have. Hope I helped.