So my GT is put away for the winter...I keep it at my grandparents house, parked in their driveway.

When I visit them on Sundays, I start the car up and let it warm up.

Today, started the car and went in the house. Five minutes later I came back out. I noticed that it was past halfway on the temperature gauge, so I threw the defroster on maximum heat/maximum fan- it was cold. The air was not even warm.

So I popped the hood...I was assuming I had a stuck thermostat...

The upper radiator hose was hot.

The lower radiator hose was not warm.

WTF?

Doesn't a warm upper radiator hose indicate that the thermostat is working? How is it even possible that the upper hose was hot and the lower hose was cool?

I didn't have time to look the car today and probably won't until next week...now that I'm home though, thinking about it is driving me crazy. WTF could the problem be? Some sort of block in the cooling system?