wrote in message
...

Yes. The exemption you describe is for wall mount units that slide
into a permanently mounted sleeve.


I think you may have that backwards, although the OP's wording in the
original post was a little ambiguous.

A wall unit that slides into an existing space or sleeve can be removed and
it is therefore not a capital improvement -- it is tangible personal
property. It is taxable as would be the cost of paying a contractor to put
it in.