Vent control question and part #???

[ksmmspt]

Hi all,

Do you know the part # to the valve that controls the vent and allows air to blow out the main vents instead of the upper/lower areas? Mine on my 85 hangs up and makes a loud pop when it finally switches over. I've got the dash out and I'd like to get a new one to replace it. Thanks in advance,

 

[turbofish38]

Vacuum selector switch.

GM-16037778
Delco 15-71389

 

[ksmmspt]

I see that this part is part of the face plate. Is this what I need? What about the loud clunk I hear near the glove box? Is this valve causing the delay in switching the air flow from the upper/lower vents to the middle area? I hope you know the answer as I'm in the dark. Thanks Eric.

 

[bad V6]

Sounds like you have a vaccuum leak in the selector switch. The switch itself goes to the back of the ventilation control assembly. Yes, it will cause a delay in the switching of the air flow, or even not allow it to be switched from the defrost/heater to the dash vents. I picked one up at Advance Auto for about $18, part #36694. Hope this helps.

Pat

 

[turbofish38]

Loud clunk is from the vacuum actuated doors opening or closing. There is supposed to be a layer of foam on those doors to keep them quiet. Its not uncommon for the foam to flake off especially after 20 years. If its clunking when you switch from hot to cold than it could be the temperature control lever. Drop the glove box door down and you can see it. Look for the cable attached to a plastic lever bent in a 90 degree angle. Its plastic and they will break eventually. Part number for the plastic lever is 3037629.