Diagnose fan selector switch?

[Gary]

When I switch from floor to defrost to panel, etc on the heater control, it just stays blowing out of the dash vents. Kind of a pain because in the winter time the windshield won't defrost till the cab is so warm it's stifling.

I've did a search but haven't found much so how can I diagnose where and why the selector is failing to change my air from one to another setting?

If there's already a post or faq about this feel free to link it to me.

[bowtiecb]

have you checked your vacum lines

[Gary]

no I haven't, where should I look? Under the dash or hood or where?

[Slonaker]

If the vacuum lines that come through the firewall get disconnected this can happen. Sorry, but I can't remember where they are...

Slonaker

[Gary]

Ok thanks sounds like I need to get my hands on some good manuals for the truck and get under the dash and start poking around.

[Slonaker]

I would look under the hood first. I have had your problem twice, and both times something that came from the firewall just needed to be reattached under the hood.

Manuals are always good, though. Some are available for free download on the auto zone website, but I don't know if they will have what you need.

Slonaker

[TireSmoke420]

check the vacume lines on the back of the a/c controls first