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Bizarre Fan Noise

To my horror, a new sound started in my car today. When I turned on the heater, the fan was very loud. There’s kind of a fluttering noise, like a paper caught in a fan and the overall fan noise is much louder, kind of howling. Worse with higher fan speed. The fan works fine, though. It does it on any temp, and also with the A/C.

What happens when you change over to A/C or turn the temperature down?

If you have parked under or near maple trees in the spring, one of those seeds (whirlybird) may have gotten past the fresh air vent screen (below the windshield) and filter(s) and lodged itself in the squirrel cage (fan).

I notice that sliding the temp gauge all the way to cold stops the sound. It does it only on heat. I would’ve sworn that when it first happened it was on any temp, though.

I like Roadrunner’s idea. I was thinking along the line of a blend door/vacuum issue.

There’s probably some debris (leaves or something) stuck in the fan. This is common, and usually works itself out when whatever is in there gets worn down enough to unstick itself and get blown out through one of the vents.

Depending on the age of your car (you didn’t specify) the fan bearings could be going bad, which will make the fan howl, but your description sounds more like something stuck in the fan.

If the noise doesn’t go away soon, you could have someone remove the fan and inspect for debris or worn bearings.

If something gets blown out a vent, will it come flying out with enough force to hit me in the eye? Stop laughing, I’m not kidding!

It’s a 99 Subaru legacy sedan. If it’s the fan bearings, is that expensive? I really appreciate everyone’s help.

No, it won’t hit you in the eye or do any other damage (it won’t “poke your eye out”). I’m not laughing, and I’m not kidding.

Usually these things turn out to be a piece of debris from trees, and they are small when they come out of the vents. It may come out the floor vents and you’ll never see it.

It’s hard to imagine the fan bearings are bad. I have a '96 Legacy, and my fan is fine. There are no reports of ventilation fans failing on late-model Subarus, or on Subarus much older than yours.

Give it some time, and cross your fingers. With any luck the noise will stop soon, just as quickly as it started.

I agree that the fan motor could be bad causing the howl, but I’d rather think there is debri in the fan, as others have said.

While it is probably something like leaves that are lodged around the fan, there is also the possibility that it could be the fan motor or even the resistors that control fan speed.

When my '97 Outback was about 2 years old, I first experienced what sounded like debris caught in the heater blower. A few weeks later, the blower began to emit a whining/howling noise, but only on certain speeds.

A trip to the dealership resulted in a diagnosis of a bad resistor in the blower motor. The blower motor was replaced under the bumper-to-bumper warranty, and the service manager stated that there had been “some issues” with the blower motors on Outbacks of that vintage. 9 years or so later, the problem has never recurred.

It seems to have “blown” itself out, and my eyes are still intact. I guess you guys were right! You rock!

A bad resistor in the blower motor??? Well we’ll never know will we??