my fridge repair guy told me that losing freon is very rare in his experience.
when he showed up i had already cleaned the hell out of the coils. i blew it out with compressed air. he said it was the cleanest he's ever seen an old fridge.
he literally cleaned the condenser fan, changed a tiny electrical unit (plug and play) and it got so cold so fast. if i remember he felt something get cold (or was it warm?) and felt the freon charge was healthy.
good luck. i know this was probably no help
