E450 Dash Air Condition Issue

[MrJackSprat]

This is more of a Ford question than a Jayco question, but in our travels today we found that our dash air conditioning (AC) seems to freeze up after an hour where little air flow comes out of vents. When the fan is turned to high you can hear it blowing somewhere but not through the vents. AC fittings inside of engine are frosted over and not sure if that is normal or a contributing factor. If we turn the setting to Vent from AC then in about 2-3 minutes the air flow returns to normal. At this point we turn on the AC and all is Ok for another hour or so. We are on day 1 of a 17 day outing. No big issue, but want to see if an issue that can easily be remedied on the trip or awaits a Ford garage appt when we are back home. We have a 2015 E450 Greyhawk.