You will be looking at a bunch of money to have an a/c company
disconnect the unit and move it off, then reconect it. How old is the
unit? I would figure out a way to do a patch job as others have
suggested and wait till the unit has to be replaced. If you do have it
done, and later it has to be replaced, you just wasted that money. We
use precast concrete slabs, as well as some that are like fiberglass
over foam. We use the precast ones where the ground is uneven and the
slab has to be partially elevated with bricks or blocks, and use the
others where the ground is level, or we can place the lightweight ones
over an existing slab if it is sound, but not high enough to meet code.
I used one of the plastic ones like Stormin mentioned when I instaled my
parents unit in 1995, and it is holding up fine. Got no idea why yours
is failing. If you really wanted to, you could probably raise your unit
just enough to get the old slab out, level the ground under it and
install a precast slab. You could get 2 pieces of angle iron long enough
to extend about a foot past either side of the unit, put one flat edge
under the legs with the other edge facing up and carefully raise it and
block it about an inch above the slab. If you are careful the copper
lines should have enough slack in them to move that much without any
problems. Good luck Larry BTW, I just bought a 36x36 precast slab a
couple of weeks ago. According to the counterman at the supply house, it
weighed 108 lb`It cost $20.48. Of course that price was wholesale, so
you may have to pay somewhat more retail, but it still should not be
terribly costly.