Samsung RSH1NHMH Buzzing Noise, but stops when door opens

Last week our fridge freezer has stated to make a buzzing sound.

The buzzing sound stops when the door is opened (sound doesn’t immediately cut off its sound a motor that slows then comes to a top over about 2 seconds), this starts up again when the door is closed.

I’ve check all the obvious things… anything that might be vibrating, checked the fridge is level, check theres enough space around the back for air to circulate. Taken off the small back panel at the bottom I’ve hoovered any dust off the exposed parts at the back that I can see.

The origin of the sound itself seems to be coming from and area 2/3rds down the to the right hand side of the fridge on the back.

Ive also noticed a small build up of solid ice on one of the screws on the inside of the fridge.

I’m no refrigerator engineer but I’m guessing it maybe or may not be something thats freezing over maybe a fan, so first thing I will try is a defrost.

The unfortunate thing is if that the warranty ended 7 weeks ago… just my luck if there something seriously wrong with it!

Any ideas what the problem might be?

Thanks

Wayne