You say the seals are not good. That lets in air, and air has moisture in it.
The frozen moisture has iced up the insides of the fridge where you can't see so the internal fan is blowing over a small block of ice rather than over a freezing set of cooling fins.
Some of the noise might be the fan chipping over the ice block which has grown into the fan. If it's a metallic scraping noise that will be the most probable explanation.
The cheapest fix is just turn it off for a day at least, leave the doors open and maybe blow fan into it until the water stops dripping out the bottom of it.
You can also fix the seals while you're waiting for it to defrost.
This sort of stuff happens mostly in summer time when the door is being opened a lot by small people opening the fridge and staring inside as if something really nice is about to appear in there. Sometimes it does, which reinforces the habit. I know that 'cos I used to do it.

Cold jelly,..

Ice cream,.

fruit salad

fizzy drinks ,.
If you've got lots of money to spare, call up a repair man. He can turn it off for half a day while he's pretending to do a complicated repair, and then turn it back on having done nothing except wait for it to defrost, then charge you $400 for a really big repair.
edit,.. Oh, chris has sort of said it already, so,.. what chris said.