Heater controls

[rustyk5]

My truck came from GM with a/c but now does not have the compressor or some of the plumbing. I don't want to put a/c back on the truck, but my heater controls dont work right. It seems to only blow air out of the floor vents and wont change to defrost etc. when you move the dash selector. Has anyone out there gone through this. Possible fixes?
Thanks

 

[arveetek]

The heater and a/c controls on the dash are controlled by vacuum. The vacuum source on the diesels is the vacuum pump located in the rear valley of the engine. Verify the vacuum pump is pulling a strong vacuum, and that all hoses and vacuum lines are in good shape.

The doors that open and close forcing air out on the floor, dash, or defrost are also controlled by vacuum.

Casey

 

[rustyk5]

I'll check on that. Thanks for the info. You and Rene seem to know these things inside out!

 

[nstarry]

I was just looking for the same info would anybody know where to start looking my a/c was removed before I bought the truck so I couldnt begin to figure out where this line would be (vacum line)
Dont mean to hijack If thats what I am doing

 

[rustyk5]

No problem, it's all good! I wouldn't mind knowing myself

 

[nstarry]

top

 

[Buckshot62]

I had a similar problem a few years back on my old (85)k5.
The door broke off where it was riveted to the control rod.
Air heat&vent only blew thru the floor vents.
hope this helps