My 2011 F150 Ecoboost air conditioner vent temperature will cycle from 49 to 54 deg. About 6 or 7 times a minute. The outside air temperature is 80 deg. I would expect more than a 30 deg drop from ambient plus it never stays at the colder temperature more than a second or two. Consequently it just doesn't seem to get as cold as it should. Dealer checked pressures and freon levels and said all is normal. Anyone seeing similar cooling?