Is it manual aircon or dual zone?
If manual, I would bank on it being the resistor pack. Switch is easy to check tho.
If dual zone, could be either .. as the electronic panel has a history of failure.
Found out and sorted the problem.New fuses kept blowing so got access to blower fan ( a bit of a pig to get at and out) fan shaft was seized. A spray of WD 40 cured it. Apparently water ingress from the pollen filter area is one cause of shaft rusting and seizing causing fuse to blow.