Units come pre-charged now. My new central air unit was pre-charged at the compressor for 50ft of line. You need to still seal the lines to the unit which requires something hotter than a propane torch(acetylene), then you should purge the lines with nitrogen, have HVAC gauges to verify the pressure holds, then evac with a pump watching the gauges again. Those are some pricey one-time use tools. Some mini-splits now have DIY connectors and precharged lines to work around those issues.
When it comes to pricey one-time use tools, I’ve found that I can come ahead by buying online (used or from Asia) and reselling it locally once I’m done.
It’s the tools I keep that end up costing me. I might need that 2nd jack, 3rd ladder, always nice to have a bucket of 10mms, bike rack for changing tire 1x/yr.
