Samsung RS21DCNS - Fridge not cooling

[Iconax]

Hi all,

Thought I'd try a thread in domestic (didn't get a reply in Technical)

I have a 6 year old Samsung RS21DCNS and have been through the defrost problem (twice). I had a new defrost kit including back panel two years ago which replaced the fan and housing. I've recently replaced the defrost sensor, the evaporator defrost heater, the drip tray defrost heater and the thermal fuse. When I hold the door switch in the fan runs for a while then cuts out and then runs and then cuts out etc. If I press the power freeze and power cool buttons at the same time to get the diagnostic, I get the bottom right light which is error '4' R-FAN ERROR. Does anyone know if this is actually the fan (which is working) or some controller I have not been able to find as yet?

[tonto33]

rear fan near the compressor see if that working