Vacuum Controllers (HVAC Controls)

[69hurstolds]

I changed the small valve that I could hear leaking. I can't hear any more leaks but still only have the floor and defrost working, squat out of the vents, hopefully fixes it. I got one of the new bulk ones on Ebay, much cheaper than the $100 Canadian the AC Delco replacement is now.

Actuator pod leak??? The one ABOVE the floor pod on driver side? (#4)

 

[69hurstolds]

Most G-body actuator pods are GM p/n:
(From the diagram above)
#4 Defroster/dash vent- 1996728
#5 Floor- 1996729
#6 Air inlet- 1996685 - this one fits all body styles in the 80s.

Nearly every body style in the 80s used the same round port selector valves on the head unit controller. So as previously mentioned, if you're junkyard digging and run across this stuff and need it, it's not a bad idea to snag the port valves if you need one or both.

 

[olds307 and 403]

Actuator pod leak??? The one ABOVE the floor pod on driver side? (#4)

No the smaller two port valve on the head unit was leaking. Thanks for the exploited view.

 

[awspeich]

I see that since this thread got active again, I thought I would add a question. I recently picked up a 86 Grand Prix 2+2, and it has the same issue, with HVAC on the defrost and floor only. When on Max AC it does come out the vents though. But with my glovebox out, I can see the junction for all the vac hoses, which appears tight. Aove that is the heat/cool cable, and the clip where it fastens to the infamous plastic arm that breaks. MY arm is still good, but my question is, where that arm goes through the heater box toward the firewall, there is a ton of air coming out of that opening. Almost like all the air is routed from there. Is there a gasket or something that is supposed to be here to stop the air from coming through? Thanks.!

 

[69hurstolds]

Foam seal. I lifted this image from oldsofb in his build thread.

 

[bracketchev1221]

I got mine from Scoggin Dickey in Texas last week. It is listed as 50 something dollars, but shipping puts it over 70. All other places are showing not available. I THINK amazon has the 2 port switch 15-72236 for like $11.

 

[69hurstolds]

I got mine from Scoggin Dickey in Texas last week. It is listed as 50 something dollars, but shipping puts it over 70. All other places are showing not available. I THINK amazon has the 2 port switch 15-72236 for like $11.

Wrong part number for the 2 port switch (Delco p/n 15-7975). Your part number shows a 6 port switch.

2 ports ain't cheap when you find them apparently

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The 9 port is a bit easier to find but pricey still. (Delco p/n 15-71389). I think they're even making repros of it maybe? Not sure.

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Here's a pic of the parts book. G-bodies NORMALLY should use a 9 port and 2 port switch.

 

[awspeich]

Thanks for that exploded view....helps a lot. So is it true then that the violet hose is the only source of vacuum for all the HVAC controls? That helps narrow it down, such that if I have vacuum on the violet hose, everything under hood should be OK.

As to the box image, that is a perfect view of what I am missing. Where the heat/cool rod goes through, I have no foam. Just a big opening. Is it possible this is why I don't have air to the vents, because I am cooling the back of the glovebox? 🤔