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Discussion Starter #1
I did a search here for "heater groan" and got no results, so I started a thread of my own.

I got into the car this morning (in a 72-degree garage) after having left the heater at the four-click position blowing last night when I shut the car off.

I immediately heard a groan after I started the car, and when I shut the heater off to see if i could hear where the groan was coming from, I noticed that it went away. I turned the heater control up to two clicks and didn't hear the groan. At three and four clicks, though, I did. When I turned the control back down to two clicks and one click, the groan went away.

This has never happened, and I have had the car since it was new.

As I drove around, I noticed that the groan went away, even at the four-click position, and when I turned it past four clicks to five and beyond, that didn't bring the groan back.

Maybe it has something to do with the fan's not being sufficiently warmed up? The car was parked in a 72-degree garage, though, so I'm not sure why that would be an issue.

I will monitor this and see what happens. Just curious whether anyone has ever experienced anything similar and, if so, what the solution was.
 

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Everything in Moderation
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Your fan motor might need a drop of lubrication. Just a drop...

Perhaps another Gen4 owner can comment on how to access the motor?
 

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Discussion Starter #4
So, the dealership looked at the car today.

It is not as simple as I had hoped.

The culprit, the mechanic said to my service adviser (I didn't speak with the mechanic directly but overheard him talking with the adviser while talking with me), is something called a heater box. I just did a search for that term here and came up empty. Apparently it is something that cannot be fixed; it can only be replaced. The cost with parts and labor would have been $2,900 (I didn't get a breakdown between parts and labor, though the service adviser indicated the labor would have been very intensive because the heater box is right behind the dashboard).

The mechanic said there was no harm in continuing to use it as it was as long as I could live with the noise. I asked if it would eventually lead to the system's no longer producing heat, and the mechanic said it was difficult to say either way. It might, or it might not. The noise might get worse, or it might not.

I declined to have the work done and am just going to live with it for now. The heat works fine, and the noise does go away after maybe a minute or two. If the system ever stops producing heat, though, I will have to have the heater box replaced.

It's really disappointing that something that expensive would malfunction after six years of being used infrequently; the car has just over 36,000 miles on it but of course is three years out of warranty (I didn't buy HondaCare or any extended warranty, and so the heater box is not covered, I was told).

So the lesson is: Don't let your heater box go bad, or you will be facing a hefty repair bill just like that! ::snaps fingers::
 

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Discussion Starter #5 (Edited)
I just did a Google search and found a link to a 2012 CR-V that had a failed heater core. I came back here and searched for "heater core" and found this thread (https://www.crvownersclub.com/forums/14-problems-issues/34722-2012-honda-crv-lx-heater-core.html). I wonder if my mechanic or service adviser just didn't know the correct term and called it a "box" instead of a "core." Apparently a lot of 2012 CR-V owners in 2013 and 2014 were having problems with cool air coming out of the passenger-side vents while hot air came out of the driver's-side vents. I've never had that problem (I checked TSB 14-063, and my VIN isn't among those affected). Some of the more recent posts (2016 and 2017) apparently relate to some kind of heater-system flush that has to be performed to get the system to generate heat. But again, heat generation isn't my problem -- yet.
 

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Your issue has to do with the fan, I thought?

If you leave the fan off it is quiet. If you turn the fan speed up (when 'cold') it groans?

Try searching for '2012 heater fan repair'

Here is a video I found. Its probably similar to your 2012?

 

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Discussion Starter #7
Thanks, Carbuff2. The mechanic who worked on the car initially thought it was the blower motor, but upon replacing it with a new one, he still heard the noise, and that was when he determined that it was the heater box.
 

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Sounds like a blend door motor since you've replaced the fan

Humor a crazy idea- check your coolant level-low levels can create noises.

Whether the expense is worth it, is up to you. I wonder if it's just lack of use by the prior owner who never changed the settings.
 

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Discussion Starter #10
Thanks, genuser and Rocky. Genuser: I tried to record a video of the sound a few minutes ago and for some reason didn't hear it. That was the first time I've not heard it in a week; I had heard it last night when I got back into the car after one of the dealership personnel retrieved it for me. So I don't know what to make of it, but I'm not complaining.

Rocky, the dealership did a multipoint inspection, including fluid levels, and I was told that the only fluid that needed topping off was the brake fluid, which was a little low. (Which itself is odd given that I just had the brake fluid flushed and replaced in June and have driven only about 2,000 miles since then, but the adviser said there was no sign of leakage; it was nothing to be worried about.)
 

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There's a possibility that you have an air bubble in a heater hose. That bubble is prone to stay in place for an extended period of time and never move, dissipate, or show up as a low coolant level. I have seen this condition a few times, and it caused a groaning noise. I would check the condition of the heater hoses, and the heater control valve. If there is an air bubble, you can bleed it out by loosening the clamps at one clamp position at a time and squeezing the hose there until coolant comes out. Sometimes this will release the air bubble. It's also possible the inner wall has collapsed on one of them, which would not be detectable on the outside, so replacing the heater hose or hoses would solve that. Also bleed at the heater control valve, which also has the potential to be leaking air into the hoses, though rare. An air bubble noise could be heard inside the car. So, all this could be an involved, though relatively inexpensive process. Another possible solution would be to power fluch the coolant system, which might, or might not push the bubble out, but it might be worth a try before pulling and replacing hoses. But there is another, even more likely possibility, too:

Some year models of CR-Vs have poor or absent screening in the fresh air cowling and intake duct (most vehicles do, and always have), which feeds directly into the heater box/plenum (which is not the same as the heater core enclosure). So leaves and twigs and bugs. etc., can easily get into the heater plenum, which is where the air control doors are. This can jam a door and either cause it to groan when one moves, or prevent it from moving, causing its actuator to make noise trying to operate it. I would check this first before anything else. Also, the dealer's ridiculous idea of replacing the entire unit is insane, and I would never go back there as that is just a blatant attempt to rip you off, IMO. Remember, dealerships do not employ real mechanics, just parts replacers., and that service writer is not a mechanic, he's a salesman, whose job it is to get as much of your money as he can. You would have to at least partially disassemble/remove the plenum to get to and remove any foreign objects. I have done this many times, and found such things as pencils or paper clips that fell down the defroster ducts off the dash, and leaves, twigs, etc., from the intake cowl. Usually, when I have done this, removing the obstacle solved the problem with no further expense. It is a pin to get to, requiring a fair amount of work, but not as difficult as one might think. And, if you get in there and find no foreign objects, you are where you need to be to determine what door is causing the problem and fix that. Those actuators are available individually. You should never, ever have to replace an entire plenum, with actuators and all.


This would be my first guess as to what your groan is. the heater hose bubble would be second. It's very hard to say without being able to hear the noise. But I would try the above and see what happens. I hope this helps. Keep us posted. And, oh, yeah, one other thing. I learned long ago to always shut off the heat/AC before shutting down the engine. Every time. It is very hard on that system to leave it on, not only when shutting down, but also when starting back up, for a whole bunch of reasons.
 

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Discussion Starter #12
Wow, there's a lot to unpack in this reply, Kloker. Thanks for the thoughts.

I live in an apartment, so I don't have the facility to do the work you describe (and neither do I have the ability to do it). I am among the least mechanically inclined people on the face of the Earth.

The noise is back; I tested it this morning and filmed a video clip, but it's in the .MOV format, which this site apparently doesn't support. I can't find any information on how to convert an .MOV file to a JPEG file on a MacBook Pro, so I don't think I'm going to be able to post a video. If anyone knows how to do this, I'd be grateful if he or she could share that knowledge.

Maybe I will ask for recommendations for an independent mechanic and take it to him and see what he thinks about your proposed solutions.

I will keep in mind your advice to always shut down the HVAC system upon turning the car off. Thanks.

There's a possibility that you have an air bubble in a heater hose. That bubble is prone to stay in place for an extended period of time and never move, dissipate, or show up as a low coolant level. I have seen this condition a few times, and it caused a groaning noise. I would check the condition of the heater hoses, and the heater control valve. If there is an air bubble, you can bleed it out by loosening the clamps at one clamp position at a time and squeezing the hose there until coolant comes out. Sometimes this will release the air bubble. It's also possible the inner wall has collapsed on one of them, which would not be detectable on the outside, so replacing the heater hose or hoses would solve that. Also bleed at the heater control valve, which also has the potential to be leaking air into the hoses, though rare. An air bubble noise could be heard inside the car. So, all this could be an involved, though relatively inexpensive process. Another possible solution would be to power fluch the coolant system, which might, or might not push the bubble out, but it might be worth a try before pulling and replacing hoses. But there is another, even more likely possibility, too:

Some year models of CR-Vs have poor or absent screening in the fresh air cowling and intake duct (most vehicles do, and always have), which feeds directly into the heater box/plenum (which is not the same as the heater core enclosure). So leaves and twigs and bugs. etc., can easily get into the heater plenum, which is where the air control doors are. This can jam a door and either cause it to groan when one moves, or prevent it from moving, causing its actuator to make noise trying to operate it. I would check this first before anything else. Also, the dealer's ridiculous idea of replacing the entire unit is insane, and I would never go back there as that is just a blatant attempt to rip you off, IMO. Remember, dealerships do not employ real mechanics, just parts replacers., and that service writer is not a mechanic, he's a salesman, whose job it is to get as much of your money as he can. You would have to at least partially disassemble/remove the plenum to get to and remove any foreign objects. I have done this many times, and found such things as pencils or paper clips that fell down the defroster ducts off the dash, and leaves, twigs, etc., from the intake cowl. Usually, when I have done this, removing the obstacle solved the problem with no further expense. It is a pin to get to, requiring a fair amount of work, but not as difficult as one might think. And, if you get in there and find no foreign objects, you are where you need to be to determine what door is causing the problem and fix that. Those actuators are available individually. You should never, ever have to replace an entire plenum, with actuators and all.


This would be my first guess as to what your groan is. the heater hose bubble would be second. It's very hard to say without being able to hear the noise. But I would try the above and see what happens. I hope this helps. Keep us posted. And, oh, yeah, one other thing. I learned long ago to always shut off the heat/AC before shutting down the engine. Every time. It is very hard on that system to leave it on, not only when shutting down, but also when starting back up, for a whole bunch of reasons.
 

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Everything in Moderation
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After you click EDIT, click ADVANCED, then you can remove attachments or totally delete the post. (There IS a time limit; if its something you really need fixed I can do it for you.)

You cannot attach videos directly; instead, upload them to the hosting platform of your choice and link to the vid.
 

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Discussion Starter #14
Thanks, Carbuff2, but there's no button or link on that Advanced screen that allows me to delete a post. I just wanted to delete Post 13 and now Post 14, given that that was just a reaction to not being able to delete Post 13.

Thanks for letting me know we can't upload videos directly. What are some examples of hosting platforms? (I never post videos, obviously.)
 

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Funny... there is a DELETE section on my screen (right at the top). I actually need to scroll down to edit the text of A message. (Win10 computer)

I'll delete the two posts for ya. :eek: (Now, they are all renumbered.)
 

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Atwell - There's no Delete function on mine either - W10 machine. You must have the super deluxe special dispensations version.

pjaymac -



Wow, there's a lot to unpack in this reply, Kloker. Thanks for the thoughts. I live in an apartment, so I don't have the facility to do the work you describe (and neither do I have the ability to do it). I am among the least mechanically inclined people on the face of the Earth.

The noise is back; I tested it this morning and filmed a video clip, but it's in the .MOV format, which this site apparently doesn't support. I can't find any information on how to convert an .MOV file to a JPEG file on a MacBook Pro, so I don't think I'm going to be able to post a video. If anyone knows how to do this, I'd be grateful if he or she could share that knowledge.

Maybe I will ask for recommendations for an independent mechanic and take it to him and see what he thinks about your proposed solutions.

I will keep in mind your advice to always shut down the HVAC system upon turning the car off. Thanks.


I gotcha. I guess I'm lucky - I have a house with a garage, tools, knowhow, AND the services of the best mechanic I've ever run across in Austin when I need him, which I frequently do these days, since I am getting old and I'm not all that enthusiastic about sliding around underneath a vehicle or standing on my head under a dash these days. The only thing I can tell you about finding a good one is that it is best done by word of mouth. It took me 20 years to find mine, and it happened by accident when a friend mentioned him. He's been my go-to guy for years now, and for me, he'll even make a house call. He owns a small shop and has one employee, who is also a great mechanic. I can do many things mechanical, and I do have the big Snap-on Roll Cab and even it won't hold all my tools, but I don't have a lift, or diagnostic tools, and most of my special tools are for working on woodworking machinery and air compressors, not cars.

So, just one (?) more question, since you revisited the noise: Can you be more specific about where it is coming from, or describing the sound, or precisely when it occurs? If it is in your plenum, you could try moving some controls around to see if you can make it happen, like switching from recirc to fresh air, from heat to defrost, from floor heat to dash vents, etc. These controls activate and move the doors in the plenum around to direct air flow from the desired source (Heat/AC/Fresh Air), to the desired output location, such as floor vents, dash vents, defroster vents. These noises would be heard through the vents, but not from the engine compartment. A bubble in a heater hose would be heard in the engine compartment, but could also telegraph through and be heard out the vents in the car. Noises have an uncanny way of doing that. In the old days the heater control valve under the hood, and the plenum door actuators, were all vacuum-operated using dashpots, but nowadays the actuators are electric solenoids with voodoo electronic computer-controlled magic.
 

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Discussion Starter #18
Atwell - There's no Delete function on mine either - W10 machine. You must have the super deluxe special dispensations version.

pjaymac -







I gotcha. I guess I'm lucky - I have a house with a garage, tools, knowhow, AND the services of the best mechanic I've ever run across in Austin when I need him, which I frequently do these days, since I am getting old and I'm not all that enthusiastic about sliding around underneath a vehicle or standing on my head under a dash these days. The only thing I can tell you about finding a good one is that it is best done by word of mouth. It took me 20 years to find mine, and it happened by accident when a friend mentioned him. He's been my go-to guy for years now, and for me, he'll even make a house call. He owns a small shop and has one employee, who is also a great mechanic. I can do many things mechanical, and I do have the big Snap-on Roll Cab and even it won't hold all my tools, but I don't have a lift, or diagnostic tools, and most of my special tools are for working on woodworking machinery and air compressors, not cars.

So, just one (?) more question, since you revisited the noise: Can you be more specific about where it is coming from, or describing the sound, or precisely when it occurs? If it is in your plenum, you could try moving some controls around to see if you can make it happen, like switching from recirc to fresh air, from heat to defrost, from floor heat to dash vents, etc. These controls activate and move the doors in the plenum around to direct air flow from the desired source (Heat/AC/Fresh Air), to the desired output location, such as floor vents, dash vents, defroster vents. These noises would be heard through the vents, but not from the engine compartment. A bubble in a heater hose would be heard in the engine compartment, but could also telegraph through and be heard out the vents in the car. Noises have an uncanny way of doing that. In the old days the heater control valve under the hood, and the plenum door actuators, were all vacuum-operated using dashpots, but nowadays the actuators are electric solenoids with voodoo electronic computer-controlled magic.
Thanks, Larry. You are, indeed, lucky to have all of those things. I have queries out for mechanic recommendations among a few family members, so we'll see what develops on that front. Hoping I can find someone reliable.

Thanks for explaining what the HVAC controls do. The sound is happening with Recirc off, and it doesn't matter to where the heat is directed -- defrost, floor, dashboard vents. I admit I haven't tried it with the Recirc on. It sounds exactly like a cow mooing. (I *have* managed to ascertain that there is in fact no bovine in the engine compartment, so there's that.) The sound gets louder with every click upward in intensity on the heater-control dial and softer with every click downward. It does sound, as the dealership mechanic said, as if the sound is coming from behind what Honda calls the MID screen (where the backup camera displays).

See if this link to the video works: https://youtu.be/V7I2-k37WJ8
 

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The link does work, and I listened to it several times - can't hear anything like a cow mooing. I do hear a fairly high-pitched whirring sound (the fan) and a low frequency sound as well. Maybe the mic is just not picking it up in a way I can hear it. Based on what I do hear it is remotely possible you have a bad bearing in the blower motor, but I think it more likely there is a leaf or leaves or other foreign matter that has fallen down through the fresh air intake cowl into the plenum and is oscillating/vibrating/singing in the wind of the air flow. I don't know if it might be possible to use a vacuum to suck it back out of the cowl, or possibly through the floor heat duct, but in my past experiences with this sort of stuff I always had to pull the box out and take it apart to clear it out. This job requires a fair amount of dash disassembly on most cars. A few times I actually found a huge pile of leaves, and one time, in the winter, the high heat set the leaves on fire while I was driving my old 80's model F250 down the street. It took me two days to take it apart, clean it out, and get it back together, but cost nothing as there was no damage done. Once, on a different vehicle, I found a pencil stuck/wedged in between the fresh air - recirc door and the side wall of the plenum, and the door moaned when opening and closing. That was another fun job, also no cost, just a lot of work. Back in the old days the plenum and heater core box were integrated in a lot of vehicles, which made the job much more involved. Nowadays a lot of the heater cores, and the blower motors, are in the engine compartment and the plenum is inside/under the dash, or variations of that. Some of those configurations make certain chores much easier, relatively. But this is really all just guesswork on my part as I can't really hear what is happening clearly in the video. I haven't had enough time to familiarize myself with my '07 CR-V yet, and yours appears to be a later model. You might find some YouTube videos on this if you search for it.


In the end, if I was there and could directly listen in person, I could probably figure it out, or at least narrow it down. So hopefully a good mechanic can too. Hopefully the info I've shared and whatever you see from others here will help you communicate with the mechanic.
 

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Discussion Starter #20
OK, thanks for letting me know the video worked for you, and indeed, thanks very much for sharing your thoughts about what might be causing the sound. (The low-frequency sound is the problematic one. It sounds more like a cow in person.) At least the sound can be easily reproduced for the mechanic, which is not always the case when vehicles have problems. If I can find an independent mechanic, I will definitely relay your theories to him and see what he says. I'll report back when I finally get it fixed.

Interesting to read about the things that you found to have been causing the obstructions in your vehicles!
 
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