New Penguin ll AC freezing up

We got two new units for our camper and a few weeks in we noticed our bedroom unit was freezing up figured it was low on Freon so we exchanged for another new unit.. we put it in and it worked great for 2 weeks but I walk in today after work and it’s warm in the camper.. I go to the roof and well this one is freezing up too… did I get two new unit from factory low on Freon or could it be something else???!