If it's working well for the 6 hours, then the Freon charge is good. Outside high humidity will get inside a pop up easily, and it'll freeze up. Try it on high fan, and let us know exactly what happens.
Every day's a learning experience, though sometimes not what we expected.
2012 Jay Flight 19RD
2016 Ford F150 XLT 2X4 SC 3.5L Eco Max Tow
2010 Tundra TRD DBL Cab (Traded)
1 Spoiled Dog