samsung RL39WBNS - keeps shutting down

[frost-free]

Can anyone help?
This appliance, according to the customer, keeps shutting down and defrosting. The only way he can get it to work is to swich off at the socket and back again. It will run for a short period and then no go.
There is no excess ice build up around the evaporator and I have tested all the components down there with a multi-meter and all are in-circuit. There seems to be adequate evaporation and hence the 'system' seems ok.
Does anyone know the correct resistance values for the derfost termination thermostat or what is the most likely fault ??
I have searched for PCB board prices (the ones under the top fascia) and the large module is available at around £100 retail however the smaller board is shown as obselete. Don't suspect the user board in this case.
Any help at all from anyone would be greatly appreciated.

Frost-free

[mikeref]

I had this happen on an L.G once,a side/side domestic. It ran for about 12 hours then shutdown.Turning off the power effectively reboots the fridge pcb, then off it runs again.I had the service manual emailed to me which was some help.the problem in this case was electrical connections inside the fridge, i believe moisture and some corrosion were causing the PCB to detect changes to component resistance.I disconnected all plugins then reassembled. no further problems have developed....hope this helps.

[frost-free]

I had this happen on an L.G once,a side/side domestic. It ran for about 12 hours then shutdown.Turning off the power effectively reboots the fridge pcb, then off it runs again.I had the service manual emailed to me which was some help.the problem in this case was electrical connections inside the fridge, i believe moisture and some corrosion were causing the PCB to detect changes to component resistance.I disconnected all plugins then reassembled. no further problems have developed....hope this helps.

Thanks Mike, I did do this when I tested the defrost components and removed the PCB boards to check them for burning.

[spimps]

Normally shuts down if the defrost heater or heater circuit is faulty.RE start clears the pcb,check crimped/multi connectors and pcb for failed joints.

[stevesmifff]

Samsung now change main board and compressor on all these models with this fault.
Let me know if you still require these parts as i can get them direct from samsung.
cheers steve