How to isolate a refrigerator?

Upon further investigation, it appears, that vibration noise is coming from the AC unit located outside of the house, next to the wall, where my system is. Initially I thought, that it couldn't be the culprit, since the AC unit sits on the concrete platform, that is simingly is not connected to the basement wall, but maybe I just cannot see the whole platform, since it covered with soil, and it is somehow is transmitting to the house.
I will try pads under the AC and see what happens.
The fridge is a little tricky- it is squeezed in b/w the kitchen cabinets, so it's unclear, how I should put pads under it? I will have to wheel it out of that space, then put pads inder it, and then what? How do I move it back into the space? Engineers here- need ideas. I'm clueless.
I only have one idea sofar, actually two- one, is to put sliders under the pads, two is to put pads on the floor, then put a sheet of peg board, ot plywood on the top, and then wheel the fridge on the top of the plywood/peg board.

Maril555 that A/C unit is most likely sitting on a concrete covered foam platform that HVAC companies use when doing installs. They dig down about 2-3" and through some sand down to work this foam platform down into it and level it. There really should be no transmission of vibration from mthe unit to the house except through the refridgerant lines. It really is de-coupled from the house.
As far as the refidgerator. I would try to have a freind tip the "empty" appliance forward and use one of those "grabbers" you see in some hardware stores for people to reach items on upper shelves, and place the pads under each rear corner. Then lift the front and slide the pads under each front corner. Just a suggestion.

Theo,
thanks for the info. I'm certain now it's the AC unit, that's causing the problem. The noise in the basement is VERY loud. I can put my hand on the wall and feel the vibration.
I tried rubber and cork pads under the AC unit- no difference, noise is still there.
One thing though- it doesn't seem to be level. Could that exacerbate the problem?
I was thinking of putting the unit in a sand box, sitting on the top of the concrete platfom, it's sitting on now.
The other thing is the lines going from AC into the house.
The hole in the wall, the lines go through, is filled with some kind of elastic material, which seems to be dried out.
Do you think the lines can transmit significant amount of vibration?

Electrically I would suggest putting an Audio Prism Quiet Line filter on the fridge outlet. That does help keep the grunge from the fridge off the house line.

As for mechanical isolation I would suggest looking at the same things that you use in an audio system ... sorbothane pucks and such under the culprit, additional bracing in the floorboards and support struts, etc.

PTM,
The noise is strictly mechanical in nature and is coming from the AC unit, located outside of the house, close to the basement wall, where my speakers are