My son and DIL bought a used Thermocore mini split when they turned their attic into a nice large MBR suite. The Thermocore was in use at a school and became available when the latter renovated.
They had a local schmuck install it at their place (kind of a hack job) and in 2 years it has never worked. The biggest problem is that no local legit HVAC company wants to look at it because they don’t handle that brand and didn’t install it.
When I was down there last week, I took a deep dive on it, and found a service manual on line, poorly translated from the original Chinese. There was at least one bad sensor (high refrigerant pressure) and either a bad second sensor (low refrigerant pressure) or no refrigerant, or both. (When I bypassed both sensors, the unit worked, except it didn’t cool).
Armed with this knowledge, they were able to get the local HVAC people to come out. There was, in fact, no refrigerant. But before they can put more in, they have to check the whole system for leaks; $200 just for that. Then add any tubing and other part replacement, plus the refrigerant. And who knows if they’ll guarantee their work.
Anyway, my overly-long story has a point; make sure you get these things installed by someone local and reputable who is familiar with the brand and is willing to stand behind it, or you may end up with an expensive headache.