please help my baby needs heat in the truck second post and thanks for all the answer

[eclipsegt123]

Hi guys i posted an add on here yesturday regarding my 03 f350 6 liter would not pump good heat. I was told to change the thermostat and heater core.So my husband did. My engine temp is around 192 but when im on vents and turn my 4x4 on it goes to defrost and blows cold for about 4 minutes then starts to pump the heat again. my automatic hubs dont work when the heat is on vents. My truck blows heat but like i said when i put it into 4x4 and my heat is coming out of my vents is changes to defrost but when i put it back into 2 wheel drive the heat comes out of the vents again. My husband thinks it a vacum leak but he doesnt now where to look. Would anyone have a diagram on the vacum line or what else could it be. please help we are - 40 here today and my baby needs heat so she doesnt get sick. Thanks so much guys

[Lilpooh]

You posted the same questions last month also. Did you follow the advise that was given, and did you look at the PDF files that were posted?
heater problems and i have a baby that i need to take in my truck

[eclipsegt123]

what are the pdf files. please tell us we need to fix this issue. can you post them again please. thanks so much

[Lilpooh]

Originally Posted by eclipsegt123

what are the pdf files. please tell us we need to fix this issue. can you post them again please. thanks so much

Click on the link on my first post, go down to post #5 that Keith T posted, you will find the PDF computer files for vacuum system.