need help with defroster

[black85k10]

I tryed to search but could not find an answer. When i turn on my defroster i get air out of all the vents including the defroster but when i turn it just to heat it comes out the vents only. So i guess my qustion is is there something blocked keeping the vents from closing or would it be one of the vaccum switches? I have checked all the clear vaccum lines under the dash an they are all in good shape

Its a 1985 k-10 with ac (350 if that matters)

[black85k10]

never mind i found the problem. It was a plastic piece that is screwed on to one of the flaps. I did see that in one of the post now i just need to find the part number again.

[gwgdog66]

never mind i found the problem. It was a plastic piece that is screwed on to one of the flaps. I did see that in one of the post now i just need to find the part number again.

Is this the one your looking for?

http://forum.73-87chevytrucks.com/smforum/index.php/topic,22320.msg185076.html#msg185076

[black85k10]

yep thank you. just ordered it

[gwgdog66]

yep thank you. just ordered it

I need to replace mine also.