I'm new to this forum, so I don't want to make any enemies, but my lager chest is not frost free and is a top loader, which reaches temperature and holds hit for a real long time - it hardly runs at all for holding a lager temperature between 45-55F. Maybe it cycles more than if I did things differently, but I have always taped the thermistor to the side of the fermenter at the krausen line wrapped in some bubble wrap.
I don't know the reasoning fully, but the beer is pretty good.
Cheers!