how to convert an old fridge?

[bkov]

how do you know where is safe to drill through when converting an old fridge? is the door always safe or might there be lines and wires in it?

 

[ChshreCat]

If there are no lines or wires connecting the door to the rest of the fridge, then you're fairly safe. Look along the hinge side and you can see. Not a guarantee, but if there are no lines there then it's unlikely you'll hit anything.