Just a point of information:
Prior to the introduction of Ethanol into automotive gasoline, many years ago now, it was customary in the winter for people to buy a product called HEET and pour it into the gas tank. The idea was that the alcohol in HEET would mix with any water in the fuel system and carry it on through the engine, not allowing it to collect and freeze in the fuel lines or other low spots.
Actually HEET was not ethanol, but methanol. And, not as good a water absorber as ethanol.
So when "Gasahol" came out, with 10% Ethanol, water in our fuel systems became a thing of the past. That also worked well for the gasoline storage tanks, whether in the ground or above ground.
Now the topic here, is that when an engine gets hot, it quits working.
My question would be, "is the engine actually exceeding its normal operating temperature?"
Or, is something else shutting down the engine when it is still operating within normal parameters?
As an electro-mechanical troubleshooter of long standing, I'd love to tackle this problem, up close and personal.
If the coolant is still the original fluid installed at the Kia factory, I'd certainly give the cooling system a thorough Flush & Fill, with an antifreeze mix capable of protecting the engine at temperatures found in the area where the car is being operated.*
* Here in FL, the standard 50/50 pre-mix is more than sufficient.
Does the heater put out HOT air when set to maximum? If the water pump was not working, it could not force HOT coolant through the heater.
That would truly be an interesting case to troubleshoot. Wish I were there!
Good Luck!
FL Hamster