I've done a lot of furnaces doing plant maintenance. I never worked on ac and don't have the equipment. But I did stay in a holiday inn express last night.
Then good thing for you it's winter.
Watching people I consider masters with the Tig never gets old. I can weld. But on something tedious like repairing A part for a pistol that is no longer available I take it to one of them. Know your limits. If you want to expand them you need pedal time.