Mature Maple problem

[Jace]

Not sure exactly the deal here. Couldnt get good photos of the branches, but there was what looked like cankers on a few of them.

Diseases of Bark

Digging near the tree(Left) was done 1-2 yrs ago for propane line. Homeowner did the digging himself, said cut roots were ball under 2". Air conditoioner is on a pad on top of ground, no digging.

 

[LegDeLimber]

I'm just armchair quarterbacking here...
can't claim any real knowledge of tree care.

But I can't imagine any way that the hot dry air discharged
from that compressor unit is helping the tree.
(have seen it "cook" some smaller stuff)

and don't block off the air flow from that side of the unit, not good for it.
edit: also that location makes for a pain in the butt keeping the leaf litter
etc out of the compressor unit.