2008 Panel LT2 2.4L 5sp.
Recently started every few days, on morning startup the climate system would make a flapping or pulsating door sound for 5-10 seconds.
That frequency has increased although all turning control knob routes correctly during running & working correct and no noise. Air flow routes to correct location: defrost, dash, floor and mix.
The AC, Heater and recirculation all work correctly on both heat & air.
No smell, no heater leaks, dry floor at both home & work parking.

I was leaning towards on a leaking control head, but every thing works, no leakage noise so not certain.
Also thought maybe a bad vacuum hold valve in the line... but wasn’t sure these even existed in this chassis.

It consistently makes about 8-10 pulsating flapping actions before stopping and operating correctly.
This was probably a common issue I’m guessing; so I thought I’d ask the forum.

 

They haven't used vacuum switches in cars forever.

Not so much common, Probably some sort of obstruction, like some bit of foam got unglued.

 

Yup. Probably something in the ductwork itself. Maybe in the fan housing? Hard to know, but Don is correct. No vacuum in these puppies...

 

Sounds like something to look at... was this a commonly occurring issue on these?

Only odd part is it's not consistent each start... might be 3 starts in a row, then none for 2-6 starts.
If obstruction, I would think it'd be consistent and also not just when first starting the HHR. I'd think by adjusting the damper door it'd fuss even during running.

That's kinda why I thought vacuum... acts like once it's built up after starting it's fine until shutdown and a leak off. But you're correct... now that I recall when changing control head last Spring there weren't vacuum lines and I don't hear leakage now... just my quick oversight.

Just thought I'd check in with you HHR Pro's on some common issues before I looked to deeply.

Thanks,
Doug

 

When you start the car it re sets itself every time. If the obstruction stayed out of the way no problem.

The doors and actuators are a common problem as the car ages. There are even Dorman repair parts.

 

The little actuator motors on the AC doors go through so sort of start up cycle when you crank the car. It may be one of those motors is on the way out or the linkage in the housing is binding or loose. Since they do the cycle at start, that's why you hear it then since they're activated.

There are some older threads about this type problem if you want to try searching for them. But, I only recall a couple threads about it so it's not a common issue with the HHR.

 

Have you replaced or disconnected the battery recently? It's not unheard of for the blend door actuators to flake out after taking a small jolt from reconnecting the battery.

 

This should explain your issue,

https://www.chevyhhr.net/forums/gene...ctuator-57384/