I’ve got a rattling noise in the fan area behind the dash (Toyota Corolla 2008). It starts when I turn on the fan in the cabin, with or without A/C. It’s like a leaf fluttering or playing cards in a bike wheel. So, I assume debris (perhaps even a dried leaf) got into that area? Is that a good guess?
While paranoia is making me think the A/C is not quite as powerful as it used to be, I don’t think that’s truly related. A couple of times I have had to turn the air off and back on to get it started but it runs OK.
If it is debris, is it necessary that I fix it? I am assuming the dash would need to be pulled out? which seems excessive for what I think is an annoyance. If I did have them look, what is involved and what can I expect to pay?
If you have to turn it off and on a couple of times, I am assuming that you can tell if it’s running or not by whether it’s blowing air? If so then I’m with JWT Kottekoe. It’s probably the blower that’s going out and not debris. It could be a bad bearing or it could be that one of the plastic fins has broken off and it’s unbalanced, or some other similar type of problem.
On some cars the fan is relatively easy to replace. You just disconnect the electrical connection and unbolt a couple of bolts and it drops out the bottom underneath the dash. With other cars you have to disassemble part of the dash and that gets a bit more involved.
As long as it blows air there’s no legal requirement to have it replaced (at least in states I am familiar with). And if it fails it just stops blowing air, so it’s not a major safety issue either, though you will lose your defroster which could be an issue in bad weather. The legal/inspection issue of it blowing air comes from being able to clear your window if it fogs over. So if you want, you could drive it around as-is until it fails, but if it fails then you do need to fix it right away because of the fogging issue.
The expensive part of the AC system is the compressor, and that’s up inside the engine compartment. A failing compressor doesn’t affect the blower fan or the air being blown, other than if the compressor stops working the air that blows won’t be cold any more.
If the AC doesn’t seem as strong just because it’s not blowing as much air, then it’s likely that your only problem is the blower motor. If the air is blowing fine but it’s not as cold as it was, then that’s a more serious problem and you may also have a problem with the compressor or the refrigerant.
Debris isn’t completely unheard of. Sometimes critters will crawl up in there and leave nuts or other things inside your air system. You can check for debris when pulling out the fan to take a look at it as well.
It’s either debris in your fan cage, mice love to build nests in those, or the bolt holding the fan to the motor shaft is loose. It has nothing to do with your AC refrigerant system. Crawl under the passenger side of your dash (with a light) and see if you can find the back of the blower motor. It will look like, well, the back of a small electric motor. You may get lucky and it will be right behind the glove compartment (you’ll have to remove the compartment door, then the compartment body itself). If you can see it you can probably remove it by taking out a couple of mounting screws, and the motor/fan assembly will just come out of the heater/AC box. Then you’ll be able to see the problem and correct it.
There’s no legal, i.e. safety reason you have to fix it, but it might get worse (it definitely won’t get better) and it will start to drive you crazy! I know it does me…
Thanks everyone for your comments! I think I would still have a professional do the work but it’s good to know it’s a relatively straightforward job. And that it’s not going to blow up the car.
Well, note that they said it’s relatively straightforward on some cars-- on others it’s a colossal pain in the butt. Some casual googling does seem to suggest it’s just the “take out three screws” variety on your car, so it might be easy enough to pull it out yourself to check for debris or replace it.
I did try to google but couldn’t find specific instructions – let me know if there’s a good place to look for this info.
More data: it doesn’t always make the rattly noise, it comes and goes. Also, when I turn the fan up to the highest setting (5) it blows pretty hard like normal and then will very slightly get a tiny bit weaker and then resume. Not a huge difference but not in a regular cycle either. But I’m attuned to it now so I could be hearing something that happens all the time regardless!
In my experience it’s usually this. I’ve had to clean out mouse nests at least half-a-dozen times on various cars. The worst is the smell; it’s about impossible to completely eliminate the stink of mouse urine. My advice is pull the fan out & make sure.
Your Toyota should have a cabin air filter. They are pretty easy to get to and often people just pull them out without replacing them. That can allow things like leaves to get to the fan.
Also it’s often easy to see the fan and motor when you replace the cabin filter. You might be able to see if there is something in it like a leaf. You could also spin the fan using something like a long screwdriver to see if it spins easily. Note: it won’t spin entirely free; however, you shouldn’t hear and scraping noises while spinning it.
A clogged cabin filter can definitely cause the AC and heater to not work as well.
Here’s a youtube video that might be for your car.
OK, cool! We did take out the glove compartment to see if we could see anything obvious. I did have the filter replaced but haven’t done it myself yet, so this will be good to see how to do that too. My glove compartment doesn’t even have the screw on the side so it will be even easier. Thank to you and everyone for all the advice.
Update: with the help of your clues and a video on-line, I was able to identify the blower motor, take out the filter, and feel around in the fan area. It spins freely and I don’t feel any pieces of anything missing or that shouldn’t be there. Unfortunately it seems like a much bigger job than three screws to get it out of there. We took those out and it’s attached a lot of other places and didn’t budge without the screws in.
So I sent away for the repair manual just to learn what it would take to fix it. Some of the screws were put in from above so it probably means opening up more than the glove compartment.
I think the issue might be the motor itself because listening to it with the motor showing, it gets stronger and weaker in blowing the air, like the motor isn’t consistent?? The air filter didn’t have any real stuff in it, just a layer of dust as expected.
This doesn’t make sense to me. Three screws, with their heads pointing down (unscrew from below) are all that hold the blower motor into the case, similar to if not exactly like this diagram. If it didn’t fall out, it’s probably just a matter of the motor’s sheet metal mounting flange sticking to the case and some gentle prying should pop it free.
I don’t know what screws put in from above you’re talking about, but whatever they are they don’t hold the blower motor. I can’t help but wonder if you removed the wrong three screws in your attempt to remove it.
Hi Gary T! Long-time fan. (no pun intended) You are correct, I did remove the wrong screws. I thought it seemed too easy given that the tips I read mentioned having to lie on your back to do it! Yep, I think I was looking at the ones in the sort of framework holding the motor in front. Back under I will go! Thanks!
Okay. Note that the fan blade (squirrel cage type, the white part in this photo) is several inches tall and a close fit in the case hole. You may have to move some trim piece and/or carpet plus do some creative wiggling to get it clear of the case.
If you decide to replace the motor, it may look like this. The blade will have to be transferred to the new motor; it’s held on with a spring clip or a nut. You may also have to splice the new motor’s wires to the original plug-in connector. If so, check the direction of rotation on the old assembly before taking it apart (plug it in while it’s lying on the footwell and turn the fan on low to see which way it turns). Make sure the replacement turns the same way or it won’t move air properly. The direction of rotation can be reversed by switching the two motor wires.
And another way to tell if your blower fan isn’t running in the right direction is your fan resistor failing very soon after the blower change and the replacement resistor failing too. Please don’t ask me how i found out. :o
Question for Gary, Greasy, Rick or other Auto repair Guru’s
So you removed the blower and didn’t pay attention, how would one determine proper rotation?
And clogged Cabin air filters lead to failed blower resistors also.
the fan’s bearing may be going or lack lube. it may someday seize up and smoke. keep an eye and ear on it. It may be difficult to extract. Get an owner’s car repair manual for that make/model.
& Good Luck!
It is an incredibly difficult diagnostic.
Plug in the motor, turn it on.
If air blows out of the vents you got lucky
If the vents are sucking air, you got it backwards.
So, yeah, it turned out to be beyond me. There seems to be a metal plate installed below the motor with all kinds of electrical wiring headed into it, and I hate to disturb something like that. But, I am glad I learned what I did about it so I don’t sound like a complete doofus when I take it in.
Thank to you and everyone for all the advice.
