Portable AC troubleshooting

Sorry if this is a little off base from the usual systems discussed here, but apart from scale it's the same bits, right?

I've got a Hisense AP70020HR1GD that I bought from Costco in 2020. It's a 10k BTU (ashrae) dual hose AC with heat option. It lives in my lightly insulated garage woodshop and keeps things bearable in the NC summers.

Three weeks ago I moved this guy from under the window to a dedicated spot with two permanent 6-inch through-wall ducts. The vent caps are a little restrictive (down to 4-3/4") but I couldn't find any that weren't like that. On the flip side, way shorter duct run than before. I cleaned the evap coils with a finxcel tool and NuCalgon that I rinsed/drained thoroughly (five years of sawdust, I was kind of amazed it still cooled at all). I did add a coarse prefilter borrowed from an air purifier but there's no way that restricted more than the caked fine sawdust.

It worked fine for 3 weeks post move. Cold air inside, vigorous hot air blowing outside just like before.

Yesterday I walked in to nothing blowing and an E9 error message, which as best I can find is a "low airflow" error. The manual is no use, of course. I power cycled it by unplugging for five minutes and took off the intake filter I'd added for good measure. It powered back on, the inside blower ran, and the outside vents sucked/blew air. But zero cooling.

I got the shell off and:

• it only has one capacitor, labeled on the schematic as the run capacitor. It tested within .01 micro farad of its spec.
• I ohmed the compressor and got C-R 1.0 ohms, C-S 2.1 ohms, R-S 2.8 ohms. None of the three terminals showed a short to ground.
• the compressor was really damn hot. I'd let the system try to do something for probably 10-20 minutes before unplugging. After reassembling and trying again, it still blew like before with no cooling. I put an ammeter on the circuit and got a steady 5.5 amps so the compressor is definitely sucking power.

I feel like I'm at the end of my troubleshooting ability - don't have a manifold gauge (and didn't even see test ports, though I wasn't searching for them). If there's a leak (or the compressor is shot) I can't imagine it would be cost effective to fix anyway. But, good people of this sub, is there anything else I should check/have overlooked before I drag this thing to the dump and spend another $500?