My soleus mini split is cooling very good but it start making funny smell after a few hours. I called a technician and he called the engineer of the company and they did some changing in the gas pressure but it only got to a point where the AC was not cooling. we gave up on the engineer knolage and re- vacuumed the system and put new and the right amount of cooling gas and it is back to normal but with the same issue of the smell.
The fan in the indoor unit never stop cause that is the way is was made and now we are thinking of installing a relay to stop the fan when the compressor outside stop, cause there is a good chance that the smell starts only when coil is not cold.
any suggestion otherwise to the symptoms? is there a special reason for the smell to appear only after a few hours? there is no leak of any kind, the drain is not clog and the coil seem to look clean. is there any liquid to spray on the coil to kill any bacteria that could make that wired smell? I read that a lady had the same problem but she cleaned the filters and it got better with no luck here.
please suggestion.

Sounds like you are headed in the right direction.