Second idea sounds like a possibility plus the freezing up sounds like what mine did as well...
We were running the Main AC on low plus it was over 100 outside, maybe it did freeze up. Even though the fan was on low it seemed to be blowing even less air than what low would normally be. I turned off the unit and turned it back on a few minutes later and it started working a gain. I ran it on high. Had both AC's on nearly 12 hours per day and at night the main unit set at 70 would cycle on and off. for 7 days... Issue seems to be infrequent but usually happens when you need it most..