Pat, I use the Mitsubishi split units in my garage and great room. I spent a little extra and got the H2i hyper heat pump so it would work if weather got super cold. 100% @ 5 and 74% @ -13. Even so they work so much better above 32 and for air. My inside units are the fancy 9K and 18K that work off the 1 outside multi zone 24BTU unit. Is yours multi zone or do you have 2 outside units? Are you using it for heat and air or just air?

These are the units I have. https://skipthewarehouse.com/mitsubishi-mxz3c24nahz2u1-24000-btu-hyper-heat-heat-condenser Great looking garage. Mike