Chevrolet Repair: no heat, heater hoses, vacuum lines

Question
astrovan has 170,000 miles.  the fan blows cold air.  was told that a vacuum line or the blend door is not opening.  i am not able to find where the blend door is.  is their a diagram for the vacuum lines or maybe this is not the problem? please advise. thanks

Answer
Hi Talip, I don't know where you could a diagram for this other than buying a manual.

  The first thing you need to do is make sure that the hot water shut off valve is working. This part is located under the hood and is inline on the heater hoses. With the van warmed up make sure that the hoses are hot on both sides of the valve. Should have hot water going in and coming out of the heater core. If you don't then you want to check the valve to see if it is opening and allowing water to flow through the core. The valve should open and close as you move the temp lever from cold to hot.

    Let me know what you find           Mark