Zanussi ZX79/5S1

Went to this FF for “warm fridge and freezer not freezing properly”. There was some ice build up on evaporator, which i cleared and all the heaters and sensors checked out ok. The strange thing is when i turned it back on the compressor kicked in for about 5 minutes and then cut out. Also i noticed while the compressor was on the condensor fan was running for about a minute or two and then cutting out for about 30 seconds and coming back on again.The compressor and condensor fan continously did this while i was there even while on super freeze. Is this a sensor fault or the rear board as i suspect? Any help please?

Thanks

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