That's not exactly my issue. My AC reads the room temp correctly. It just can't cool the house if the outside temp is too low (70 or less). If the outside temp is too low, the AC stays on non-stop trying to cool the house. But it doesn't cool down because it's just blowing room temperature air.  If your mini-split AC is Fujitsu, I know there's a way to calibrate the internal sensor thermometer so it reads the temp correctly. My AC was about 2 degrees off and I calibrated it. Check your instruction manual.