I have a 2013 Hyundai Sonata that is overheating only when the AC is on and I need to fix the problem. I wasn't sure if it could be a relay or if there is a way to check the relay. I'm not very good with newer cars after 1980's.
Is the fan and radiator in good condition? I would start there.
If the fans are good, maybe the AC compressor is going out and put too much strain on the engine.
See if you electric fan is spinning with the ac on if not assuming its electric,jump fan directly to battery. If it works replaced radiator fan module if not replace the fan.
This is how I did it on my 2007 Lincoln town car, Your 2013 sonata I am guessing is somewhat different. Why dont you get a factory repair manual on paper or dvd that is how I learn the basics for fixing my car.
Good Luck
