2013 g37x, When i first start the car, the heat blows hot, then goes cool. Turn the heat up, it gets hot, then will go cool. This all started today after being on the highway 10-15mins, 20-25mins or so after the heat was working fine. The coolant rez isnt low, the temp guage doesnt fluctuate. Its not only hot when driving, it hot even at idle, it will then randomly go cool, even on the highway.

 

Today it seemed to work better with the AC on. I turned the AC off the last 5mins or so until i got home, didnt seem to get cool. It was set at about 75-76 the whole time. I didnt test it on full heat, but around 85-86 yesterday during one of the rides, i believe it stayed hot then. But anywhere from 70-82, it would get hot when first turned it on, when first turned it up, but would get cool. Driving conditions didnt effect it differently. Today when it worked pretty good was all city drivin, though yesterday city driving and highway driving it would get cool. Im thinking either a door blend, or the climate control/module itself. More leaning towards the climate control