As others have mentioned, it’s not your A/C that’s misbehaving, it’s the engine cooling system that’s falling short. It can’t handle the extra heat that the A/C condenser dumps onto the radiator.
A low coolant level, most likely due to a leak, is one possible cause. With the engine cold, check the coolant level in the radiator and top up if needed. If it was low, find and fix the leak.
Poor coolant flow could also cause this. Usually this would be from a partially clogged radiator, faulty water pump, or malfunctioning thermostat. These are pretty unlikely on a two year old car.
A failed radiator fan would typically only cause overheating when the vehicle is stopped or moving slowly, as mentioned previously.
And it’s possible that the cooling system is not malfunctioning, but just isn’t designed to handle the load of both 100+ temperature and A/C. As a “bargain” marque, Kia may not have engineered as robustly as most other makes.
Items of interest:
Yes, the A/C helps keep you cool, but it doesn’t contain coolant. It contains refrigerant. When you’re controlling how much hotter than ambient temperature something gets, you use coolant (car engines, nuclear reactors). When you’re making something colder than ambient temperature, you use refrigerant (A/C, refrigerators).
The coolant level in the overflow jar is not a reliable indicator of a full cooling system. You need to check it under the pressure cap (on the radiator in most cars, on the engine or on the surge tank in others).