Introducing Non condensable through gages

[summerblues]

Simply conecting your guages to High/Low side would not introduce air , or could it ?

How about if I'm using a low loss fiiting on high side and when done transfering the excess freon to the low side ?

would this be a scenerio where non condensables would get in
if not properly purged ?

[hvac maniac]

If the system is low on refrigerant and the low side is in vacuum, then yes.

[4l530]

You're slapping your guages on a system that is under positive pressure in regards to atmosphere, so I don't see air getting in there by the act of putting your guages on it. Unless it's under negative pressure, which you probably won't know about until the guages are on.
Now when you dump your guages back into the system with the low-loss fitting, I could see some air/moisture getting in there if you have got some in your guages. Or if your LL fitting leaks.
But I wouldn't think it would be enough to worry about on your typical split system, unless you're doing it hundreds of times or more.