Mesh
I'm guessing the $6.99 they collect from all us victims covers this:
"If our device fails as the result of a surge, you will be reimbursed for the costs to repair or replace your damaged appliance at fair market value."
If your air conditioning is part of the house heating and cooling system, as opposed to something you hook up to the window and move around, it is more likely covered in a standard homeowners policy. Check with your insurance agent (or better still the claims people at the home office) to see if you are duplicating this coverage. Lots of times when there are insurance exclusions they apply to electronics, but not to the furnace or built in range etc. Electronics are actually better protected by local surge protectors, they are much more sensitive to surges of the type that come from things happening inside your own home circuits. Some of the relatively inexpensive plug in surge protectors come with ridiculously high "insurance" guarantees for damage of affected electronics. Those big guarantees reflect, not so much the manufacture's confidence in his product, so more the fact that this kind of damage is not as common as most people think. And of course getting paid for a claim under one of these guarantees is an act of faith.