Clicking in the background

I've never heard a sound like that in our Clarity, so I can't help you there.

However, at the end of the video I saw you press the P button. Do you know the Clarity puts itself in Park when you press the Off button? The only time I press the P button is when I'm stopping to let somebody out of our Clarity before proceeding on my way.

 

It’s the vents in the HVAC system adjusting.

 

Check the cabin filter for mice.

 

Sounds exactly like the Air Mix Control Motor. I have heard the same sound and coincidentally just had mine replaced yesterday under warranty and it seems better although it's too early to tell if replacing the part fixed it. I think the sound is probably normal but it's the frequency of the sound in my case that was the problem, it would just keep clicking repeatedly for several minutes at a time like it was having trouble deciding where it wanted to be. The Air Mix Control Motor regulates what percentage of air flows through the heater core vs. bypassing it. It operates even when using AC, that's probably normal as Honda seems to do some odd and seemingly inefficient things with climate control for the sake of maximum comfort.

At first I assumed the sound was normal and tuned it out, but over time it just didn't sound right and was getting pretty annoying because once it got started it would just keep going for several minutes. Started to seem louder the past few months or maybe I just imagined this since I was so aware of the sound by now. Besides being annoying I was concerned that it would shorten the life of the motor. It has been somewhat random, but I could often duplicate it by adjusting the temperature to a specific temperature, seems like when the AC is at a specific setting it wants to adjust the mix but apparently in some conditions it was unable to as it would keep hunting for several minutes. I suspect most people hear the sound, but if it's just a few clicks it sounds normal and people don't notice it. But when it runs for several minutes you know something is not right. Happens mostly on warm days using AC. I don't remember it happening as much during winter. Sometimes when I turn off climate the sound will continue for another minute or so although not as frequent, then it stops.

I eventually isolated where the sound was coming from by removing the kick panel in the passenger footwell, it comes off fairly easily just by pulling on it by hand and the clips will release. The arrow in the first photo is the location of the motor, all you can see are yellowish/white plastic parts you don't see the actual motor which I assume is behind the plastic parts. The second photo is a closeup of the part. The visible parts sort of rotate back and forth when it makes the sound so it was very definite that this was where the sound was coming from. If you remove the kick panel on your car you should be able to determine pretty easily if this is the part where the sound is coming from. Probably hard to see this in the photo, but there seems to be three plastic pieces sandwiched together, the center plastic piece is stationary, the piece in front and the piece in the rear rotate independently, although you only see a couple of tabs sticking out from those pieces.

If yours is the same thing you will definitely see movement within this part associated with the sound. Although if you only recently heard it, it's possible that yours is acting normally and you just happened to notice it for the first time. But if it goes on for minutes at a time then you may have the same issue.

I read about a similar problem with I think Accord or maybe Civic, the same part caused the problem, apparently inside the plastic part there is a sensor that determines the position of the rotating piece(s) which it then sends this info to the computer. The rotating parts ratchet a tiny amount at a time, thus the clicking sound. I am guessing the sensor tells the computer each time it has moved to the next position. Apparently too much grease inside the unit eventually dripped where it wasn't supposed to be, affecting the sensor when it was at certain positions, thus the constant back and forth (i.e. endless clicking) as the computer was not getting good information about the position of the rotating pieces. A couple of people fixed it themselves by removing the part, disassembling it and wiping the grease off the sensor. No way to know if that was the problem with mine, and the photos one person uploaded of the procedure, while seemingly easy to do, and the part seemed very similar, it was a slightly different part and removal would be slightly different, and certainly while under warranty I wasn't going to fool with it myself.

In September I made a video of it when it was acting up and showed it to the service writer, he asked me to email the video to him so he could show the mechanic. Mechanic came out to the service entrance where my car was and I was able to duplicate the sound for him by adjusting the temperature, although it wasn't as frequent as it was in the video but at least I was able to tell him that's the sound. I still had the kick panel off and I was able to point to the part that was making the sound. He took the car back to the service area, I didn't talk to the mechanic again but the service writer came to me in the waiting room and said the mechanic confirms that's the part and they will order a new one. This was in September, the part came in two weeks ago while I was out of town, and as I said they installed it yesterday.

On the drive home from the dealer yesterday it was quiet at first, then started to make the sound for a few minutes but didn't seem as loud. I did a U-turn and went back to the dealer, but by then it was near sunset and the AC wasn't really needed and the sound had stopped. I walked in and told the service writer about it, we both agreed I will monitor it and I'll make another video if it does it again. Today it didn't make the sound at all, only thing is it was 70 degrees, and I don't expect any more warm weather this year. But if it turns cooler and the heater is needed I will listen for it. Even setting AC to low or heat to high I couldn't duplicate it today, seems it requires something other than perfect weather. Then again maybe the new part has solved it or at least made it normal, although hard to define normal without driving another Clarity to see what sounds it makes and how often. It may take until next spring and AC is needed again before I know if there has been an improvement.

The part they replaced was 79170-TRT-A41 Motor Assy Air Mix (Passenger Side)(Passenger Air Mix Control Motor). The part was listed at $91.60, I don't know what labor was since it was done under warranty. There is another part number for the drivers side, 79160-TEX-Y61. I don't know where that one is located but I didn't hear any sounds coming from that side. Based on a diagram I saw I think the drivers side motor might be for the mix door that controls the percentage of air flowing into the cabin vents vs the windshield vents.

 

@Frankwell, thorough explanations with photos like this are what makes this forum so great! Thanks for sharing your experience.

 

I had the same problem with our 2007 Odyssey, and also pn my daughter's same model and year, but both were on the Driver's side. It had that clicking sound, accompanied by a faint water gurgling sound, and caused the driver air temp to rachet up significantly. The unit uses a stepper motor that may pick up resistance or corrosion over time, and causes it to search. On the Odyssey, it was grease that spread out over time, and on to the contactors, resulting in continuity loss. I was able to temporarily fix them by cleaning off the grease - not sure of the cause on the Clarity, but I suspect a similar problem.

Coincidentally, I think I noticed the same clicking sound on our 2018 Clarity for the first time yesterday, so I guess I may end up upside down under the dash, replacing it.

 

Follow up to my post of November 11th. I mentioned that even after the dealer replaced the Air Mix Control Motor, I still heard the clicking sound on the way home from the dealer, although not as frequent, but that could have been due to the change in weather. The next few days after that I heard the sound quite often.

So as a test I simply unplugged the blue connector that you see in my photo in post #5. And voila! Blissful silence. And both heat and AC seem to work just fine, although I have been out of town quite a bit since then so my experience with the motor being unplugged is somewhat limited. I haven't checked with my scanner for fault codes, but I suspect there won't be. Now this does mean that the air mix door is stopped in a certain position, and I don't know what that position is. But I suspect that the door is not binary, i.e even when fully moved it probably doesn't totally block the heater core. We haven't had cold weather yet, but I expect it will provide plenty of heat even with the door fixed in whatever position it is. But if I suspected that the fixed position of the air mix door was causing a problem I can always plug it back in. And then I could unplug it again during the summer which is when the clicking noise seems to be even more active.

Perhaps I am overly sensitive to it by now, but after they replaced the motor it was still annoying even if it wasn't as frequent. I dreaded that next spring when the weather warms up it might start getting over active again even with the new motor. Hard to believe this is normal behavior as I would expect more people to complain about it. But I suppose one difference is that I normally don't listen to the radio or recorded music while driving, whereas most people do. I can hear it over the radio when I have it on, although it's certainly less bothersome in that case. But many times I am stopped for a period of time checking emails etc. without the radio on, then it is really noticeable and somewhat distracting. Hard to say what another Clarity owner would say if they sat in my car while it is doing it. They might say, "That noise? My car does the same thing but I hardly notice it". On the other hand they might say, "Whoa, I don't see how you put up with that, my car doesn't do that." Just no way to predict since noise is somewhat subjective to each person. I just know that in my otherwise very quiet car I hear this nearly constant clicking and I really would like it to go away, especially since I now know that the noise comes from an air mix door that in my opinion is not really necessary (controlling bypass airflow around the heater core as a way to more quickly regulate cabin temperature). And why this door has to be active at all during summer is completely mystifying. I shudder to think that in hot weather the car actually brings warm air into the heater core, to be mixed with cold air as needed to more quickly regulate cabin temperature. But I suppose that would be no more shocking than when I found out that apparently the resistance heater is used even when the engine is running instead of using engine heat, it apparently only brings in hot coolant from the engine only in extremely cold conditions when the resistance heater can't provide the required heat by itself. I read that in a technical article somewhere, sorry I don't have the reference at the moment.