Vacuum Controllers (HVAC Controls)

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FL85GrandPrix

Apprentice
Nov 10, 2016
71
28
18
Tampa, FL
Hey guys, since I bought my 85 GP the air would only come out of the floor and defrost vents. I vacuum tested the entire HVAC controller system. All the actuators are perfect. Hoses are good. I chased the vac leak down to the two vacuum controller or vacuum switches in the HVAC panel. Turns out you can buy the larger main 9 port controller from Rock auto for $50, which I did tonight. However, our control panels have a second, 2 port smaller vac controller for the heater valve under the hood. I am at a loss trying to find this part. I actually removed and disassembled both switches and could technically replace the rubber o-ring in each if I could find it. Any help on the smaller 2 port vacuum controller/switch? If I cannot find a fix for it, I may have to just eliminate it. Stinks I had to spend $50 tonight for the 9 port swtich to just replace a worn rubber gasket with a groove pattern in it... What is everyone doing to "rebuild" these HVAC control panels?
 

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69hurstolds

Geezer
Supporting Member
Jan 2, 2006
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I can't tell you about how to rebuild them. I have a few new control head units so if there's an issue, I just replace the entire thing. That's how I roll.

Are those gaskets MOLDED that way with the Egyptian pyramid-style hieroglyphics? Or is it because that's how they are compressed? If that is how they're made, I have NO idea where you'd get new ones.
 

Gonzo1970

G-Body Guru
Sep 30, 2018
898
1,302
93
Napa has the 9 port for $27.

Napa part number 207709 A/C Mode Selector Switch

Its where I got mine, I'm just not installing it in 20 degree weather :D

-Gonz
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
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For 200 you can replace the whole thing with a new one...Pontiac parts book calls for p/n 16041112 for the whole controller:

http://rover.ebay.com/rover/1/711-5...0001&campid=5335822911&icep_item=183343525072

Ironically, the guts in a Cutlass is the same as the GP. Cannot find any entry in the parts book for the 2-port vac control in any of the books. Can find the other ports and switches (same ones, btw) for GP and Cutlass. Just not THAT one.

I thought I had one of these controllers for a pontiac, but I looked at it and no, it is not. It doesn't have that extra port control thing on it. Which is what I'm assuming you need. Kinda looks like a truck type or something.
 

a.graham52

Greasemonkey
Oct 19, 2017
105
27
28
mine had to be squeezed together to get a good seal if i remember correctly. i did something with a sheet metal screw though the center of the wheel to tighten it up. that and a little bit of grease and i havnt had an issue going on 2 years.
 
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bracketchev1221

Royal Smart Person
Jan 18, 2018
1,386
1,599
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How hard is it to actually replace one of these switches? I guess my question is more of, I expect to open the dash up and find that the hoses don't come off the old switch and are all dry rotted. Is this a safe bet? Mine is an 80 Malibu with AC, and the above condition. Air from the defrost and floor but can't get it out of the dash.
 

FL85GrandPrix

Apprentice
Nov 10, 2016
71
28
18
Tampa, FL
69hurtolds- Thanks for that info. the ebay link you shared does show the 9 port and 2 port switches!! My panel and switches are all good, figured replacing the vac parts would be cheaper but I guess now. Good info.... thanks.

The o-rings are made with a pattern for vacuum channeling. It's not from being squeezed together. If I cannot find the 2 port switch, it's pointless replacing the 9 port switch. Might as well replace the whole panel assembly.
 

FL85GrandPrix

Apprentice
Nov 10, 2016
71
28
18
Tampa, FL
Well I cleaned up both o-rings, bent the metal tabs so it's held togeter tighter, and low and behold I have no vacuum leaks now on either switch in the control panel. However, I am 99% sure I still have a leak in the purple/pink vacuum hose that goes to the engine. My question is, where can we buy the OEM style silicone flexible hose they use for the HVAC? I can't seem to find it anywhere.
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
8,088
17,308
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Well I cleaned up both o-rings, bent the metal tabs so it's held togeter tighter, and low and behold I have no vacuum leaks now on either switch in the control panel. However, I am 99% sure I still have a leak in the purple/pink vacuum hose that goes to the engine. My question is, where can we buy the OEM style silicone flexible hose they use for the HVAC? I can't seem to find it anywhere.

Not sure you can. They had part numbers from GM, but they seem to be extinct. May can find some fossilized ones in Montana.... :)
 
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FL85GrandPrix

Apprentice
Nov 10, 2016
71
28
18
Tampa, FL
Figured as much. Recap of where I'm at on the HVAC system.

-Tested all the vacuum actuators and they all hold vacuum perfect.
-Was able to re-built and get both existing vac switches to stop leaking.
-Bought a new 9-port ACDelco vacuum switch.
-Found that NOS ACDelco control panel on ebay if needed
-Still have a vac leak when pulling at the purple hose under the hood. Instead of the rapid leak it's now a slow leak. (white heater valve hose is capped off, I do not have a heater valve currently)

We're getting there.... Thanks for the help guys.
 
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