If this is a first floor, you also have to think about what's on the
OTHER side of the wall - a sleeve AC mounted near grade my have the
airflow to the condenser coil obstructed by vegetation, or may admit
water if snow drifting against it melts due to warn air infiltrating
out withing the sleeve and then ice dams, forcing melted water to flow
back between the AC and the sleeve and into the the wall cavity or
interior of the structure.
Paragon Home Inspection, LCC