Factory A/C air shut-off valve ??

[Luis_gz06]

I just installed a used air shut-off valve (Flapper) the one that goes underneath the cowl panel on the passenger side. I know these are suppose to control the outside air flow into the cab but it doesn't flap all the way!! When I pressed the vacuum actuator, it wont shut all the way. And the shut-off valve is not tight all the way with the plastic nut the goes inside. It is lose a little and when it flaps, it falls down. What can I do???

Here are some pics to see what im talking about.

[eedgell]

Have you applied vacuum to it yet?

[Luis_gz06]

Not yet! My truck never had A/C since we bought it 22 yrs ago.
When my dad bought it, it was missing alot of A/C parts and now that its almost complete, this is one of my concerns, as described above. And how do you apply vacuum to it?? Thanks!

[eedgell]

Through the vacuum system that should be there. It is turned on to there from your a/c controles inside. If it it is not all there, good luck. I have posted questions about the a/c vacuum lines before, and I got feed back with diagrams, but they are difficult for me to read. I need to see it, then I can do it, ya know? There is a whole vacuum system with the a/c cabs that run every thing! Wish I could help. Try thread searching the subject.

[Aarons72s]

Ok I will explain the vacum lines. Line comes from a port on the carb or intake, your choice. The line goes to the round vacum tank on the evaporator box. Another line comes out of there and goes inside to the vacum switch on the control panel. Another line comes off the second port and splits into 2 lines at a t undet the dash, 1 line goes to the kick panel actuator and the other goes back out into the engine room throgh the same hole as the first line. Once in the engine room it splits into another 2 lines with one going to the flapper in the cowl and the other going to the heater valve on the inner fender. This system is set up so that when the top lever is slid all the way left it applies vacum to these 3 actuators and it does the folloewing, opens kick panel flapper, closes the cowl flapper and closes the heater valve.

As to whatmay be holding the flapper open, check for excessive seem sealer in the cowl. Especially on non ac trucks converted to a/c. So look inside to see if there is to much sealer. Also there should be some adjustment on the actuaor if it needs more movement. Hope this helps.

[eedgell]

I know that helps me! Good job explaining the vacuum line route, I think I got it!!!!
much better than a diagram.

[Aarons72s]

Glad I could help. YahMost diagrams leave much to be desired. I think they should be drawn exactly how they look and to scale to.

[dan42]

Good info! now I can figure out where that vacuum line goes on my truck. Thanks -