Installing new ductless mini split AC alongside existing central AC

[Steven Kay]

For a 2 story, ~1400 sqft townhome, it rises to about 85 degrees fahrenheit on the second floor, while around 77-78 on the first floor during the summer weather. There is an existing central AC that doesn't seem to get it under 80 degrees upstairs during 90-100 degree weather and ultimately is kept running that increases the electrical bill.

Does it make any sense to install mini split AC in the 3 bedrooms on the second floor over replacing with a new central AC that should be more efficient? Considering selling the property (approached as a live-in flip) potentially in the next few years and wondering if I will be able to recoup part of the cost and increase appeal in the future. 

Thank you BP community!

[Scott Mac]

If it were mine, I would do all of the following before shelling out money for a secondary system.

Check ther attic insulation.

Consider installing UV heat repelant tint (it has a service life) on all sun side windows.

Have a thermo scan done of the exterior and interior to see where heat problems occur.

Have the AC system check by a tech for proper amount of coolant, and to see if its too big or too small.

Vent the cooking hood outdoors (if it's legal to do so).

Install ceiling fans in the hallway upstairs and in the bedrooms.

Have tech make sure the draw air system is sized (and positioned) correctly for each floor.

Make sure the thermostat is not a (NASA Project of complication designed to micro manage the temp), and that it is working correctly.

Some Techs are much better than others....

Good Luck!