*Raising hand* It is not just you at all. I have experienced this as well. When I get overheated, I get grumpy. This is so foreign to me and so not who I am that it upsets me thus making the irritability worse.

I really try to keep cool, going from a/c to a/c. It's sad how I can go from Ms. Happy, girls lets going shopping, have fun, etc. kind of person to a grump just from walking from my door to my car (maybe 50 ft or so). I will be irritable until the car itself cools down. Then I'm happy again.