HVAC Fan Rumble
 

Yesterday morning when I started up my car and turned on the defroster, I noticed that my HVAC fan is making a very noticeable rumble. I have had the car for 15 months since new and this is the first time I have had this problem. The higher the fan speed, the louder the rumble. The car is going to the dealership on Monday. Any one else experience this? I did a SEARCH and saw that someone else had noticed this problem previously with their car, but didn't seem to get an answer. I know the fan in our cars is relatively noisy, but this rumble which started yesterday is very pronounced. It sounds either like a bearing could be going or the blade is somehow out of alignment and rubbing on something.

It is because it is working harder to pull air from outside
 

It is because it is working harder to pull air from outside

Was the vent outside in front of window covered with snow?

Switch the controls to circulation, amazing sound goes away right?

I noticed this too!

The fan in my car has developed a "grind" to it when I first turn it on, there is either something in there hitting the blades or the bearing is going for some reason. As it does it worse when it is cold out and has been getting worse week to week I am suspecting a bad fan.

In either case it is soon going back to the dealer as this is certainly under warranty.

Re: It is because it is working harder to pull air from outside
 

There is no snow in the vent, as the car stays in a garage. Switching the fan to recirculation does nothing. It is going into the dealer on Monday; I will keep people posted as to what the problem is, in case the problem may arise on their cars.

I have had this happen before on cars...and what had happened was a small stick made its way through the grating/vent in front of the windshield and made its way to the fan...had leaves do the same thing...and it sorta sounded like a playing card on the spokes of a bike.....just turned the fan up to full speed till it broke off! lol then it was all quiet again.

I thought about that. After running the fan on 3 for 2 hours yesterday on the way out to my parents place, it still makes the sound. It doesn't exactly sound like playing card in spokes sound, though. More of a rumble. Time will tell when my Mazda dealership puts their mokeys on the job.

I do think it is either a broken fan or a misaligned fan as a bearing problem would reveal itself fairly quickly with dire results, especially considering how often the fan is kept running in the winter.

And then you had little pieces of leaves stuck to the evaporator of your AC unit. I think those should be cleaned regularly (like once a year maybe?). I had to replace mine recently because so much stuff accumulated in it (lint, pieces of leaves, dog hair, a bug, etc.), that it eventually rusted and leaked the gas out.

I noticed the "rumble" in my car HVAC a few months ago, it wasn't a grinding noise, more like a bass-y drone behind the fan sound. The noise has gone away!? I've been running the heat/fan alot cuz its been cold here. The sound is now what you would expect noise-wise.

I had my car into the dealer to look at the fan rumble; it did turn out to be just a few small leaves inside the fan motor cage. The dealer did the work under warranty and said there has been a large number of Proteges/P5s that have been in for this problem. My wife and I just moved into our new house recently, so it shouldn't be a problem now because it is a brand new house and no big trees (yet); the leaves were from parking near a couple of trees at the old place. Even though I always cleared the heater intake off when there was leaves and debris on it, the dealer says that the Proteges are fairly susceptable to this.

Thanks for telling us what was wrong!
 

Thanks for telling us what was wrong!