Greetings - newbie to the HHR world. 45+ years as an auto mechanic. Never thought I'd own a bowtie product, but the HHR is an enjoyable ride. Just purchased a 2011 with 39k miles. New Rotors, pads, tires. Interior barely used, nearly new all over. It was time to get real as to automotive maintenance costs and 'retirement' budget. This crate is just right! Glad I took the jump from my Volvo habit - that would deplete any SS check with just a hiccup. And I just don't have the energy - or feeling in my fingertips- to continue my rehabbing Studebaker Larks - I've owned 4, and my current 1966 Cruiser wants more of my time that I would rather spend in the hammock. I cut my teeth on the GM I6 230 cu.in. engine back in my Auto tech. school days, and I think that was what lured me to rescuing the 66. This morning I started the HHR up and was welcomed by a thumping in the cowl/center console area - was there a squirrel resting there? but it was too regular in pattern to be anything but the 'new' car. Curiously, I tapped the brake and could hear a similar but quieter thump in the same area. I have read here that it might be the air doors adjusting. Does this ABS system create a noise that anyone else has experienced? Otherwise - pretty pleased with the new ride. Heck - my wife loves it too!

 

Welcome to the site, the thumping could be the HVAC doors , to test change the settings from foot to windshield then back to face , the blend doors will let you know if there’s a problem.

Now as you stated , a thumping noise when you started it up, have a look at the air filter box bracket, it’s bolted to the back of the head



That’s one right there in it’s natural habitat, check it for cracks or broken completely

 

Well - appears to be the Actuator doing it's 12 count cycle flapping a passenger side airdoor. All air sources work fine according to defrost/dash/floor selection with fan on. I might just learn to live with it. Heck, I've only enjoyed it for a solid week! It's Peppy with the 2.4l
the cup holders could really use improving! I am sure there is a good adaptation that was found by HHR members.
thanks for the tip.

 

Welcome to the site.

 

Someone else said they had the problem your describing and the cabin air filter was in the way some how, worth a look

 

Thanks for that tip. Sent me in the right direction. and the filter was a tad dirty. but the Cabin vent shutter actuator is the culprit. Dang, but that motor is up there where you need to get a very small child's hands to do that work! and I don't know any children that want to do that. Next step - push the dash buttons for intake/closed cabin air. That'll teach it. And lo - this morning, my dear wife says - Hey, Fred - it isn't doing that thing! Satisfying, the small things. And as my 96 year old friend has always told me - Don't sweat the small things -- They are all Small Things! thanks again - glad this resource is here for the quirky HHR. Every Mechanic deep down loves a challenge. guess I won't get rid of my tools now.

 

I’m retired, and will die with my tool box still at home! Just the way I was taught and raised.