[Piwoslaw]

An 'inverted A/C system' is more or less a steam system, only with refrigerant instead of water. In this case we may use something other than water for our "steam", which would be appreciated in colder climates. But water (in a vacuum) would be OK for testing.

I'm not sure that an A/C compressor would spin when you blow air through it. The compressor probably has a one-way valve at the piston intake. Even without it, pumping air into the compressor would force the piston down to its lowest position and that's that. The compressor would need to have at least 3 pistons and some semi-complicated valve system to force air into the right piston at the right moment in the cycle. Something like a steam locomotive? Hint, hint, wink, wink

I'm not sure about reversing the newer scroll type compressors.

Soooo.... Replace an A/C system's compressor with an air motor we're getting somewhere.