I am converting my garage into a family room. Trying to figure out
whether I can tap into my existing central air or if I need to go with
a ductless mini-split.

Did a HVAC-CALC tonight.

Existing: 10,000 Gain, 29,000 Loss
Garage: 6,500 Gain, 13,500 Loss
Total: 16,500 Gain, 42,500 Loss

I have a 1.5 ton 10 SEER A/C, and a 40,000 BTU furnace.

So I am close. But is it too close? Any advice?

Thanks,

Chris