Vacuum Source for HVAC

[tucsonjwt]

Is the only vacuum source for the HVAC control in the dash from the small black/orange vacuum line coming from the passenger side vacuum tank on the firewall?

[crazeetxn]

In my '86 there is only one line coming through the firewall to the control. Don't remember the color though. I have it connected to a port off the carb.

[donut]

Mine only has one. My vacuum ball is also on the driver's side, connected to a vacuum tree on the intake. I also don't know the color, and I just put everything back together. I deal with actuators later.

[tucsonjwt]

Mine has cruise and air. Driver side vacuum tank goes to cruise control servo, then big vacuum line from servo to cruise cut out switch at brake pedal. Passenger side vacuum tank has that small orange/black line, teed off to passenger side vent door in kick panel, then to vacuum valve on the back side of the HVAC control. I just don't know if this is the correct setup. Thanks.

[crazeetxn]

What year truck are you working on? Never seen a vac tank on the passenger side. Interesting. If you take off the dash bezel, there's only a couple of screws that hold the a/c switch in. Pull it out a little and see if you're missing a hose. Not sure how the vent could work if it's on it's own vacuum source.

[donut]

Originally Posted by tucsonjwt

Mine has cruise and air. Driver side vacuum tank goes to cruise control servo, then big vacuum line from servo to cruise cut out switch at brake pedal. Passenger side vacuum tank has that small orange/black line, teed off to passenger side vent door in kick panel, then to vacuum valve on the back side of the HVAC control. I just don't know if this is the correct setup. Thanks.

I don't have cruise, so that would explain "ball" location.
iirc, the orange/black does run the vent actuator. To my knowledge, those vacuum lines aren't something you can run to Auto Zone and pick up. (more than likely unmolested) In my case, the lines under the dash appear to be intact, but what I found was the controller was installed upside down and not "switching". I didn't pull everything out, but the orange/black was visible when I removed the glove box, and somewhat easy to trace.

[tucsonjwt]

I have an 83 C20. There don't appear to be any vacuum ports on the HVAC control in the dash unused. If you have factory A/C and cruise I think the vacuum diagram shows to vacuum tanks under the hood, which is what I have.

[tucsonjwt]

I have never been able to find those tiny vacuum lines for the HVAC control, much less color coded ones. Dose anyone know where to get them?

[motornut]

seen cut ones patched with washer hose,shrink wrap

[Stoney]

Here is the hose, they have different sizes and colors.
I bought the red to match the rest
https://www.carpartsdiscount.com/aut...tml?3593=59732

[tucsonjwt]

Thanks Stoney. I have been looking for that hose for years.

[Stoney]

I actually accidently found it. Looking for GM power window motors one day.