I like to go start my car like 10 mins before I leave for work in the mornings just to warm it up a bit (damn you, winter).

The past three times I did it, after just about 10 mins, I go out, and the temp gauge is way up in the red, check gauges light is on, and the (heat) vents are blowing out cold cold air, like the AC.. If I turn the car off for 5 seconds, then start it again, the gauge drops, and it instantly blows hot air. Weird..

Then this morning, it did it again, but instead of turning it off, I just started driving. Less than a min later, the temp gauge dropped to where it should be, and instantly the air changed from freezing to warm..

Weird.. Any ideas?!

thanks!

ps - the car is a 96 Z28

 

No one has any ideas?

 

try bleeding your cooling system you could have a air pocket causing this and when you drive it or shut it off your moving the air pocket into a different past of the cooling system...

 

I agree with Iroc. Also, you might not have enough antifreeze and the coolant may be freezing.