heat issue

My 2006 Mazda 6 is over heating when I drive and then sit or if I let it sit and idle. There are no leaks that I know of and the temperature goes back down when I turn on the heat. It drives fine other wise. Anyone know what might be the issue?

Hello Mazda friends! My heat is not working for my 07 Mazda 3 i Sport. The relay fuse is not the problem, already checked that. And I don't think it's the thermostat. I'm confident it's related to the fresh air intake/circulation button. When the heat does work, i can press the air...