I just installed a new central ac/gas furnace that uses the new R410-80 coolant. The outside ac unit keeps shutting off after running for approx 30 min to 2 hours. It won't turn back on sometimes until the next day. The contractor has been here three times and just keeps "charging" the unit. The inside compressor runs fine. Any ideas? I am ready to call another contractor to check the problem.

Find another contractor. Send the bill to the first one.

Was it replacing an R22 system?
Was the lineset changed or flushed?
Were the lines capped after the old system was removed?

It almost sounds like non-condenseables or oil contamination.

If he keeps charging, then he suspects a leak and he should fix that or he knows how to install when things go right the first time.

Ty... I knew I should go with my first instinct... call a new contractor. Yes it was replacing an R22 system. Lines were completely changed. Everything is new. Go figure.