Wierd HVAC(?) Noise

[newv]

You guys out there are great at sharing your immensely helpful diagnosis and opinions - I have a weird one for you.

I have a 2006 V but posting to the larger audience here. There is a noise inside the car coming from approx the center stack. It sounds exactly like a bad blower bearing - periodic soft whirring/grinding about 1 cycle/second. It is intermittent, I can often but not always make it stop when I turn the HVAC completely off (power button), however sometimes it takes a second or two after button push to stop. Same with turning on the HVAC and making the noise start. But neither is consistent. It changes tone somewhat with faster engine RPM, but is not directly coupled. It only happens in cold weather and is intermittent enough that it is hard to troubleshoot - not enough time to change all the HVAC settings while it is happening. When it is happening it will last for minutes. I did see in searching the threads that there is a "rolling film" door in these cars - I can guess but I don't have any idea how that works - but since it appears to be a moving element perhaps it's the culprit? By the way it is definitely not the HVAC blower. Has happened two winters now, never heard it in summer with A/C. Any ideas?

 

[long Tall Sally]

I think there is a thread here on that noise. Remedy if I remember is to ignore it. I tried the search engine here and could not find it. I find you can get direct to answers by using google instead. type In key words and then "forum"

 

[newv]

Good tip on the google search, I'll try that as I did a number of different attempts at words and phrases within the site but didn't find anything related. However, you may be referring to a more subtle noise I think I have heard also. The noise I am chasing is definitely new and seems too loud to ignore as benign - not that it's that bad - but it is definitely in the category of, "something is going wrong".

 

[long Tall Sally]

so theres the "there, didyou hear it" types noises and the " oh boy, thats not good" type. Ihope you can find it and share. did you capture an audio of it on your phone to share?

 

[newv]

Good idea - I did not try the phone record. It is probably in between your two descriptions - but it is intermittent and not always loud. It doesn't sound like something is going to break immediately, more like a bearing going - you know it will only get worse and you'll be fixing it in the near future.

 

[newv]

Update - Working the Google angle per your suggestion longTS I found a link to an STS forum and then back to a different XLR forum (didn't know there was another one) but it had a posting from CCClark who is a big contributor here too. Both mentioned the temperature sensor aspirator fan - a damn tiny fan that pulls air in over the interior temperature sensor. The noise I hear really sounds like a bad fan bearing so this is making me hopeful. I pulled that fan/sensor out from behind the dash so I can watch and listen. The noise did not happen tonight after I did that but I'll see if I can catch it in the act tomorrow.

 

[newv]

This is getting maddening. It was not the aspirator fan. But it still sounds very much like a spinning element with a bad bearing. What else is turning in the HVAC system? Is there some sort of spinning valve/propeller in the coolant stream of the heater core? In manipulating the air flow position switch I seem to hear that film actuator moving precisely in short time steps - sounds correct. Since this noise starts and stops with the heater (temperature) power switch - but not exactly simultaneous - how does turning the switch on initiate coolant flow? When it first starts up it sounds like a little wobble of a fan, then the pulsating whirring of an off balance fan (or propeller?). It is certainly not normal, but it is obscure enough I don't want to take it in and have them throw a bunch of expensive parts at it randomly. I'd like to at least guide them to the right thing, Ive already eliminated the blower and the aspirator fans. Any other ideas? Anyone done a major HVAC repair and understand the components well? I guess it cold still be coming from the engine, but I can't hear it outside of the car. I captured a good recording of it , it's audio only so I have to see if there is some way I can post it. Thanks all.

 

[newv]

Had to turn the audio recording into a YouTube video.

The noise goes away about one second after I turn the heater off each time. It does not start until a few seconds after I turn it back on, and the noise comes back sounding a little different each time but you can hear it is the same source.

 

[newv]

Received one PM from someone who heard a similar noise but no root cause found. Anyone else have a chance to listen to the audio yet?

 

[ghawk]

Your hearing is a helluva lot better than mine...I don't hear anything in your video that I would notice in the car. Sorry.

Gary

 

[newv]

Thanks for giving a listen Gary.

 

[nerkpowers]

Received one PM from someone who heard a similar noise but no root cause found. Anyone else have a chance to listen to the audio yet?

Do a search on air vent noise or havoc noise. Some comments about a rolling film, might be the culprit.

Dash vent duct actuators - HVAC question
Cadillac XLR Net Forums - Cadillac XLR Forum - Cadillac XLR and Cadillac XLR-V Forums | Blog
Tim


Sent from my iPhone using Tapatalk

 

[newv]

Thanks Tim, Did those searches again to be sure and didn't find anything like my noise. As I mentioned previously I think (could be wrong) the rolling film actuators are OK. I can hear them making precise moves when I press the air path button. The noise I hear, and this is on the recording, is somewhat continuous once it gets going. Which I should have said in regard to Gary's comment - in the recording it is really when I turn the heater off that you notice what noise stops, because it doesn't start immediately when I turn the heater on.

 

[MPRCTCL]

I know this is an old post, but I found it because I’m chasing the same noise myself. Those who can’t hear it on your recording definitely would recognize it if the had it too! Did you ever figure it out?

 

[XLR-V Husker]

Anyone figure out what the noise was?