where is heater core?

[heavy d]

I might look for a vacuum leak..that may be whats causing it not to open up..thanks for your input guys..let me know if you have any more ideas

[tom4bren]

Yah, it sounds like the core is either clogged or the valve isn't opening. I'm guessing it's the valve since if the core were clogged that badly, the radiator would probably be too.