Re: Zanussi ZX99/5 No “frost free”
If you’re sure the heaters are ok (checked when out of circuit) there is an overheat cut out in there as well, check that for continuity.
Make sure you unplug it 1st 😉
There are no sensors relating to the defrost cycle that I can see, it’s all controlled and timed by the control unit.
If you’re after an engineer, which is probably the way to go, can you pop your postcode up, there’s a few engineers on UKW that cover your area but not all the postcodes.
DAve.