Best 11 in 1 is the Klein with the shrader valve core remover. It will wear out using it as a nut driver quickly as said before. Get one 5/16 and one 1/4 nut drivers instead. I have a little electricians pouch that I can clip to my side when doing service work.
It has just about every thing needed to diagnose when I first arrive on seen.
Here is what I have in the pouch:
5/16 nut runner
1/4 nut runner
Cobra pliers 6"
Ratcheting service tool with extension
Small flat head for tstat wiring
Gear wrench with 5/16, 3/8,1/2,and 9/16 ratcheting double ended wrench
Field Piece foldable thermometer
Small led flash light
this will take care of 80 percent of what you need small tool wise
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