i had two frost-free freezers. The first a Bosch died suddenly, I
couldn't find anyone to fix it and I didn't have time to try. So I
bought a "very reliable", very expensive Liebherr frost free. Which
expired suddenly a couple of months ago. i couldn't get anyone to fix
it. I got a £120 fixed price repair from Domestic and General, big
mistake. Domestic and General are purveyors of extended warranties,
they sub-contract the work out and have no customer service or quality
control. The bloke they sent levered bits off the back trying to get
to the PCB; access is through the front. He hadn't got a clue.
Domestic and General won't pay for the damage.
With nothing to lose, I had a go and found it was a thermistor.
I won't buy another frost free job. A conventional freezer uses a
passive device to cool the compartment, the equivalent of a radiator.
A frost free has a fan, a finned heat exchanger, the equivalent of a
fan-coil air blower, plus various electronic sensors and controls that
the refrigeration gorillas don't understand. If you've had any
dealings with fan-coils, you'll know they're a set of maintenance
problems in a cabinet.