Central air works great then freezes! the compressor outside is freezing, as well as the line going in?

Coils have been cleaned outside, evaporator coils inside are clean, new filter. All vents in the house are open and have great airflow. After it thaws it works great for a couple hours, then freezes again. I can tell when it freezes because the air coming out of the vents is not as cold, and not very forceful. Then the unit just runs forever, keeping it frozen until I notice. Its a Rheem 10seer with a Criterion 2 furnace, if that makes a difference. What else can I do? I don't really have the money for a tech right now :(