Yesterday the heat started blow cold on the highway on my way to work. After work it was fine and fine running errands in the evening.

This morning it was fine taking the kids to school until I got on the highway. After a couple of miles on the highway the engine coolant temp was dinging and in the red. I had to keep driving as there was not a place to safely pull over. After a mile the engine coolant temp returned to normal, but the air was only blowing warm. I got off the next exit and turned off the van for a minute. Then I started it and the air was blowing warmer, but not as hot as it should be, and still cooler on the right side. I will see what happens after work.