Pressure testing overnight isn't so great, since the cold night will condense the nitrogen
inside the copper and cause the reading to be lower..
So, to be sure.. Wait for the pressure (and temperature) to come back up to what it was when you started.?.
I say keep the pressure test going until the temperature starts changing (a few degrees).
If it's still holding, you could leave it overnight if you wanted to..
But don't be alarmed to see a lower reading in the morning.
Pressure testing is mostly for the flares. Are they tight? Soap them good.
When you start pulling a vacuum, that's when any pin-holes will show up.
Since you won't be able to pull a good vac, if there is even a very tiny leak..
And, there's always that last pressure test. When the R410A is released
into the line set, close the valve one last time and use the liquid soap.
If all is well, tell the R410A certified HVAC guy to release the hounds!!
I ran the Sanyos for about a week and went back an checked the flare fittings one last time.
Might get 1/8 of a turn more.?. Or 1/16th..