I have a bottle of Merlot in the fridge (accidentally) for a year. Is it ruined when I take it out?

Has it been opened ?

I would say yes it's ruined. Only one way to find out though.

No, it has never been opened.

Should be fine.
Only really one way to tell.

Ben,
The only reason I suspect it's ruined is that red wine is very finicky about temperature changes as you know; but since it's a Merlot with low tannins I guess you may be right about it being OK.

A constant low temp would be fine, just means it wouldn't age quickly.

After all you can buy home "caves" for storing wine. These are basically large fridges.

While "classic" cellaring temp is around 10 C lower would be OK.
Fridges don't fluctuate that much.
A lot better than the old wine rack in the kitchen as quite a few people do.