I think your options are to get your unit to a dealer right away, they are all getting busy for summer, reserach and try a modiification on your own if you have the skills, or see a local AC person to do a modification. There are two facebook pages that take quite a bit of time to scroll through and find posts, you have to join them first as they are private.
My dealer advised a few weeks ago they were waiting for the 'fix' instructions from Shasta but our problem is a bit different from yours...maybe...as we shut ours off feeling how hot it was making the cabinet area the ac is mounted in. We were concerned about the area melting as with the fluke thermometer tested the inside of the cabinet at 140 after around 45 mins of running.
Cold air blows out but the cabin would not cool. It was 80 outside and 82 inside.
I understand there is a fix now being done by the dealers but the only details I have heard is they are installing an insulation panel but no photos yet or other info other than that one comment on one of the two private facebook pages.
We and several others that I know of have modified the exhaust duct/intake with good success. At least two of us have done the install modification and replaced the unit with a 8,000 BTU unit. Two people have posted they have their 5K btu units working quite well so the upgrade may not be neccessary just the modification.
WARNING...doing your own work voids the warranty!!!!!