Blend Door for dummies?

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Evil Bob

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1988 K5 Factory a/c truck (a/c deleted by previous owner)- a buddy helped me out and relpaced my heater core (thank god for mechanic buddies). Only thing is now my vents are all screwed up. Heat pretty much come out the vents and floor only no matter what setting I have it on. My defroster barely works at all which is no bueno. I am guessing it’s my blend door ‍♂️ Is there a go to you tube video for this or a good schematic? I am too embarrassed to keep asking my buddy to help out even though it may have been something he did or didn’t do when reinstalling the heater core.

All suggestions are greatly appreciated thanks.
 

WFO

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Check to see if your vacuum line that comes out through the firewall on the passenger side is hooked up.
 

Evil Bob

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Check to see if your vacuum line that comes out through the firewall on the passenger side is hooked up.


Yep I did and it’s all good. Outside of that I am clueless with this stuff lol
 

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PrairieDrifter

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The blend door just controls temp. I believe there are 3 maybe 4 vacuum actuators that control the vent doors separately. Those need the vacuum lines to be hooked up from the control unit to each actuator.

It would have been a good idea to lube all the doors when the heater box was out. Not sure if you guys did that or not.
 

Evil Bob

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very cool thank you
 

Evil Bob

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The blend door just controls temp. I believe there are 3 maybe 4 vacuum actuators that control the vent doors separately. Those need the vacuum lines to be hooked up from the control unit to each actuator.

It would have been a good idea to lube all the doors when the heater box was out. Not sure if you guys did that or not.


I doubt it but I will be tearing it apart next and will be sure to do it. thanks...
 

chengny

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Make sure the diverter door connecting link is intact and secured to the door (and actuating arm):

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Snoots

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X2!

Those plastic things are VERY BRITTLE!!!

Be very careful with them and use some PB Blaster on them. Also, if it's very cold I wouldn't mess with them unless I had a small electric heater or heat gun just to warm them up (not direct high heat).

Don't ask how I know this.

I used to have a diagram that showed the workings of the vacuum actuator/selector switch but can't find it.

Start out with what WFO recommended tho.
 

Snoots

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Try these . . .

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Evil Bob

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thanks for all the help... My buddy broke a bunch of sh!t when he took the dash out :(
 

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