Mechanical Whirring / Brushing Sounds in Dashboard

Yes, a few people had their HVAC fan replaced. Here's the thread.

 

Is it a continuous sound while the fan is running, or more of a ticking/scratching sound that occurs only sometimes?

 

I've heard this a couple of times when I'm idling in my driveway but haven't bothered to do anything about it. It seems to be random and pretty infrequent for now so I know there's zero chance it will happen if I take it into the dealer.

 

That's why I asked, that is exactly what I experience. I noticed it within two weeks of ownership and find it annoying. I have brought it up here a few times and either gotten no replies or only a couple of other people say they noticed it. So I am still wondering if it is a defect or just a normal sound that most people tune out because it is not that loud and doesn't happen all the time. To me it's a similar amplitude as the brake switch which most people seem to hear but when that has come up it becomes a debate only about whether it is loud enough to be considered annoying. Whereas I am not sure everyone hears the sound under the dash on the passenger side that we are hearing. I think it's possible that ours is nosier than others or more frequent for some reason which is why we notice it when others don't.

To investigate I pulled off the cover below the glove box, which comes off pretty easily. Just had to disconnect a wire for a small LED light. I then observed that under the dash there are two different sounds coming from two plastic parts, both of which rotate. The larger plastic piece is blue and seems to be connected to the main blower door. The smaller piece is white and is the one that makes the ticking/whirring sound.

I suspect the smaller (and noisier) piece is connected to the door that opens and closes to allow warm air to mix in with cold air. What we are hearing is the small electric motor that rotates this piece, as well as the tick sound when it starts moving. However unlike the main door (blue piece) which rotates until it reaches its set position, the smaller white piece rotates a tiny amount then stops, rotates a tiny amount then stops, it does this maybe ten times until it reaches whatever position it finally stops at. Then it is usually quiet for a while but sometimes starts up again. In a past thread when I reported this I said I suspect that it moves a tiny amount then pauses while the computer checks the instantaneous reading in a sensor somewhere nearby, then moves it again slightly, and keeps doing this until the desired sensor reading is achieved. I can make it happen at will by changing the temperature, it seems like it's when you get on sort of a borderline temperature setting that it "fights" to maintain that temperature by constantly adjusting this door.

In further research I discovered that my theory is quite likely as there is a door that opens and closes to allow warm air to mix with cold (see attachment), I just haven't had time yet to verify that what I am observing is this same door but at the moment I assume that it is.

- Air Mix Control Motor: The system controls the temperature of air coming into the cabin by mixing the ratio of warm and cold air. The air mix control motor adjusts the air mix door to regulate the desired temperature





In one sense I am less bothered about the noise if mine is acting normally and does not indicate a defect causing it to be noisier than it should be or perhaps a defective sensor that causes it to take longer to "hunt" for the exactly right door position. I could always attach some insulation to the area to hopefully reduce the sound if it keeps bothering me, since it is loud enough at times to hear even with the radio on.

What concerns me more than the noise is even the idea that they are mixing warm air with cold when using AC. Even assuming the warm air is coming from outside (which I am not sure of after looking at the diagrams), it's just hard to process the concept that such an efficient car would bring in hot air from outside as a way to maintain set temperature when using AC. Obviously some fresh air always comes in even when set to recirculate, but this apparently increases it, or maybe uses warm coolant when it is available.

Maybe the net effect on overall efficiency is minimal, similar to mixing in friction brakes with regen for smoothness. But it should be optional. Personally I'm fine with it being one or two degrees colder in the cabin than the set temperature for a few minutes, all they have to do is cut off the compressor and the heat that is always coming in from the outside through the body panels and windows (as well as fresh air) won't take long to bring the temperature back up again, then the compressor can turn back on. It should at least work this way in Econ mode (unfortunately it doesn't), then in the other modes they can play their air mixing games if they want to.

 

I have the solution if it’s not the fan blades in the thread @insightman referenced or the door and stepper motor that @2002 researched for us.

Just take too much rock and roll from the 70s and add it to old age and all those pesky sounds will fade away.
Works for me!

Seriously though, mine is super quiet even with my hearing aides in. Or at least it was until I read the thread about the click when pressing the brake pedal. You don’t hear that one unless you are listening for it and tap instead of push the pedal. LOL

And sometimes a pairs of electrons in the battery will get quantum entangled and you’ll just barely hear Schrodinger’s cat howl (but only randomly 50% of the time).

What can I say, it’s the quietest car I e ever owned.

 

I only hear it from the passenger side, and that's where I located the parts making the sound. I suppose the sound may also bleed through to the driver side of the dash but to me it always sounds like from the passenger side.

Well we have to define "car needs to be heated", as the statement that I quoted above (entire document attached to this post) indicates that warm air is mixed with cold, so the question is where does the warm air come from. It could easily be warm coolant brought in when ICE is running, however I also hear the sounds in EV mode which could in theory mean they run the resistance heater to get their desired "blend" of cold and warm air, but I would say that is impossible just from a sensibility point of view that they would run the AC compressor and the resistance heater at the same time. So that's why I suspect they are bringing in fresh air, at least in EV mode, but the diagram doesn't indicate that. Unless maybe fresh air can also be routed through the heater core when in EV mode, but again the diagram doesn't show that, although below the diagram it says:

NOTE: This illustration is an example only. The appearance and structure of the actual parts may vary depending on the model

The brake click sound I hear is not related to the brake lights. If I very lightly press the brake pedal the brake lights come on and I hear a very faint almost inaudible click. When I press a little harder I hear the louder click that I also hear sometimes when ACC is running. Pressing normally the sounds run together which is probably why most people associate it with the brake lights. It is very noticeable unless your mind is on other things or have the radio on loud enough. If you are listening for sounds you absolutely cannot miss it and to me it is annoying. I know that usually elicits mocking replies, but to me the car is amazingly quiet, they somehow isolated just about everything, so I suspect they did not intend for the brake actuator to make that much noise and it is louder in some cars than others. So I guess what I am saying is sounds are annoying if you suspect they are louder in your car than they should be, but that is difficult to determine since there is such a range of opinion on what is loud and what isn't, and no practical way to try out several different cars to see if what I am hearing is louder than what other people are hearing.

 

I have that sound frequently in my 2019. I almost always drive EV with the radio off. I notice it most when the climate control is changing what it is doing - when the climate control is on auto and I start the car, turn into or away from the sun, or turn the climate control from auto to manual control.

 

FWIW, my climate control makes absolutely no unusual sound. All I can hear is normal fan noise and since I have ceramic IR reflecting tint, my car doesn’t get hot enough most of the time to run the fan past low speed. It may also help that I never have passengers so I close off the rear vents and passenger side vent. I’d be a little perturbed if my very quiet Clarity was making the noises you are describing.
There is a service bulletin out that adds a part replacement to the software update. Don’t know if that would help or not.

Here is some info I copied from other threads:
By Dmiko on 1/5/18
EVTC Failure Misdetection: SB 18-089
HV Range Display: SB 18-091 (seems different from the one others reported)
Abnormal water temperature reading: SB 18-090. For this one, they ordered a part and said it will take several hours and they would have to disassemble the entire dashboard.

In my case, the service advisor went to his computer, looked up my car by vin and said: you have 4 product updates available.

Posted by leop on 10/5/18:
It appears that the fix for the DTC P26A3 is now a software update mentioned in Service Bulletin 18-089, dated 10/4/2018. I was told that this Service Bulletin supersedes Service Bulletin 18-079. Another Service Bulletin, 18-090, calls for the replacement of the Climate Control Unit. I suspect that this may also be related to problems with the heating water control since the issue corrected is described as coming up when running the heater. These two Service Bulletin updates are to be done at the same time along with a new software update, 18-091, to correct the HV mileage issue. All three (3) Service Bulletins are part of a recall campaign for the affected Clarity automobiles.
Also
Yesterday (10/4/2018), my wife had another Multiple Systems Warnings episode. This time I was not there to reset things so I decided to call the dealer and get the fix (TSB 18-079) and well as the HV mileage update (TSB 18-069). The service adviser was surprised at my call as just a few minutes earlier, he was given notice of a recall campaign to fix these (and a couple of other) issues. I had the software updates done this afternoon (10/5/2018) and got paper copies of the four (4) relevant Service Bulletins:
18-089: EVTC & 3-way Valve software update for DTC's P100C, P0010, and P26A3 (this replaces 18-079)
18-090: Climate Control Unit Replacement
18-091: Driver Display Software Update (Mileage) (this replaces 18-069)
18-096: Warranty Information CD
The parts were ordered so that the service needed for 18-090 and 18-096 could be done in a future visit.

All the Service Bulletins are dated 10/4/2018 except for 18-091 which is dated 9/21/2018. The four mentioned Service Bulletins are all lumped together (all mentioned in all Service Bulletins) and the owners all affected vehicles (determined by VIN) will be sent a notification of the campaign.

Also you can run an A/C diagnostic by doing the following:
Turn on ignition, hold down Climate on-off button and press RRdefrost 5 times.

 

I had previously looked at SB 18-090 but that seems to be something different, it was apparently for some type of software error that caused the malfunction indicator light (aka check engine light) to come on. The diagnostic just basically runs the AC system through its paces, you hear the blower at various speeds, it also briefly runs the resistance heater because I felt heat even in ON mode with a cold engine. At the end of the test on the infotainment screen it shows zero errors if everything seems to be working okay.

Current theories:

1. It's a normal sound, at the same dB in all cars, but not everyone notices it.

2. It's a normal sound, but at higher dB in some cars than others, only owners with higher dB occurrences notice it. Higher dB could be parts batch related, not exactly defective but still hardware related.

3. It's a normal sound at normal dB but happening much more frequently due to software/hardware problem, only owners with high frequency occurrence hear it

4. It is not a normal sound and indicates a software/hardware defect.

My current feeling based on my observation of the parts making the noise, the likelihood that the "noisy" part is the warm/cold air mix ratio control door, and the comments from those who hear it and those who don't, is that it is probably #2 above.

Fortunately the "annoyance" factor is reduced by the fact that it doesn't make the sound all of the time, cumulatively probably just a few minutes per drive, mostly when first starting off as that is when AC is working hardest to reach the set temperature, then afterwards occasionally for the rest of the drive.

 

During cold weather, when ICE is running warm coolant flows into the heater core just like a regular car. In EV mode there is a resistance heater located in the engine compartment not far from the firewall which warms the coolant flowing into the heater core. During that time the heater core coolant loop is cut off from the rest of the cooling system and has a separate water pump to circulate the warm coolant through the heater core.