These things cost $100 to $200 new.
Is it likely they have sophisticated controls, and a reversing valve? Or a heater?
Could be, I guess, those Chinese can do some amazing stuff.
A service tech will charge a large percentage of the new cost, and may not know how to fix it, given that they don't see many of these. For obvious reasons.
Now a serious question. (anybody want to show off?)
How would you know one is running correctly? Where would you take temperatures, and what should they be? The air on these goes through both sets of coils, and comes out warm.
For that matter, would you charge these by superheat, or subcooling?