Question--HVAC blows air primarily through the AC ducts, but really also get some light airflow through the front defroster. and heater as well. (basically, blows air everywhere, but stronger fromt he ac vents.

The change in the control panel has no effect--ie, when switching between where the aif is supposed to come out, no change takes place.

I already replaced the heater controls once, and still the same issue.

I tested the "new" one with a vacuum hand pump before buttoning everything up, and it did move the doors in the hvac with the hand pump (but the air also did bleed off a bit as well.

Thoughts on how to correct/fix the issue?

 

Check the line coming from the engine for damage / loose connection.

 

confirmed vacuum into the HVAC is good using a hand held vacuum pump.

 

I mean with your eyes and fingers, physically inspect the condition of all vacuum lines under the hood. My hvac didn't work until I replaced the line that went from the check valve to the vacuum ball.

 

[QUOTE=Komet;6459082]I mean with your eyes and fingers, physically inspect the condition of all vacuum lines under the hood. My hvac didn't work until I replaced the line that went from the check valve to the vacuum ball.[/

l replaced the vacuum line from the motor to the check valve, from the check valve to the “t”, and from the t to both the vacuum ball and the cruise module. I also replaced the ball itself with a genuine GM.

 

https://www.thirdgen.org/forums/tech...ol-vacuum.html

In my personal experience, it's usually the HVAC vacuum selector on the back of the HVAC unit that causes vent issues in 3rd gens. They were unavailable for quite some time, but looks like Rick's sells them now.

https://www.rickscamaros.com/camaro-...-178318-1.html

 

how the doors and other vacuum parts work on these cars was never the greatest... its probably because the foam that seals the doors etc.. is crumbling / old.

 

I’ll order one of these and see.

I did confirm that the replacement of all the vac lines as stated above has corrected/repaired the cruise control….so system is holding vac beyond the check valve.

 

Does it hiss like it should when you move the selector?

 

only really noticeable when I move it to defrost...but it does not change anything with regard to the airflow.

 

I ordered one of these, then called eckler's for a follow up. Turns out, this part is not in stock (despite the website saying it is). In fact, it was DISCONTINUED IN JANUARY 2020!! Still showing available/in stock on the website. Had I not called to follow up, who knows if they ever would have informed me of same.

 

Try the fix for the above part:

https://www.thirdgen.org/forums/inte...anent-fix.html

JamesC

 

So, we did see this video, and completed the upgrade. I do think the valve is holding air (when I slide the hose manifold off of he switch, I get a hiss (indicating that it is holding air); however, the airflow does not change at all, regardless of the setting on the control panel.

I had also read somewhere that the system is supposed to "default" to defrost, but on my car, the default seems to be the AC vents...thoughts?

If we close all of the AC vents on the dash, the defrost does get enough ariflow, as it is forced in that direction a bit more for outlet (path of least resistance), but it is driving me crazy that it does not work as designed.

 

[QUOTE=keithl1967;6459442]I had also read somewhere that the system is supposed to "default" to defrost, but on my car, the default seems to be the AC vents...thoughts?/QUOTE]

The default is defrost. The above fixed my issue. All now is as designed. It would appear that you have another issue. Perhaps something is blocking/hindering a door or perhaps an actuator is bad.

JamesC

 

Perhaps something below will be of help.

JamesC

 

I always thought hissing was a sign of it leaking, isn't it?
Oh, and I think I still have some HVAC control units with good valves if you can't find a way to fix yours

 

One small hiss if it goes all the way across is fine. All the '80s GMs we had did it even when new. I used to like to move the levers just to hear it hiss when I was a little kid. You also want to make sure there's at least some resistance. If it is super easy like using a guitar pickup selector then there's something wrong.