heater box diagram

does anybody have a heater box diagram? I have no heat in my 99, dosen't seem to be the cooling system, as I've tried everything as far as it goes. I do heat heat for a second when I first flip it on, but it goes cold so I'm leaning toward vaccum or blendoor or something under the dash. Please help!

Thanks,
Adam

What about water flow? Did you try by-passing the water control valve?
Or at least are the hoses hot both in and out of the heater core?

it not the cooling system, core's gettin plenty of coolant...i don't have a water control valve, its a 99... I'm sure it's something under the dash..