Water is leakiing from around a tube going down the back of the refrigerator. Is this a drain tube for the defrost or part of the ice maker, which was disconnected years ago?
Can I spray some expanding foam around the large gromet or will this impede the function of something?
The tube comes out of the freezer, down the outside back of the refrigerator.
Take a look at items 315 and 226 in section 02.
Yes it is the drain line.
I would not use spray foam.
You have to figure out why there is water leaking out.
Does one of the parts need replacing?
Is it condensation because the tube is cold?
Is the drain tube plugged so that water is backing up in the tube?
I would check that it is clear.
If plugged a turkey baster with warm water, an air compressor with low pressure or a wire can often be used to clear it.
Also check that it is not plugged with dust etc. at the drain pan end.
You might as well clean the condenser/compressor fan and the condenser coils while you are down there.
If it looks like stuff is growing in the tube I would flush it with a 10% bleach solution. This should kill the stuff and let you flush it out. You may have to do this several times, let it sit for 15 minutes or so between flushes.
Be careful that the drip tray does not overflow and empty the drip tray after you are done.