While I don't recommend this, that plastic cover is the first thing that I throw away. Ken2 has the safe way to use them. That being said, I have used 3 Snapper RER's for the last 40 some years and no problems. I would not do this if children use it.
Sheenist
Bange:A simple way to determine the size and threads per inch is to find or create a piece of round wood that is slightly tapered to start in the threaded hole. Screw into the threaded hole abaou a 1/2" then remove. The marks left on the wood will tell you the correct number of threads per inch...
I agree with those that say the AC unit would need more HP than is practical on a mower. One thing that I think would work, is a good sunshade with an overhead fan. Just one old man's opinion.
Sheenist