Tonight while driving my 2003 Kia Sedona with the defroster on, suddenly I heard this very loud rumbling which sounded like it was coming from the engine compartment on the passenger side. My first thought was my exhaust had broken, but as soon as I turned off the heat blower to listen, the sound went away.

I also smelled something burning... not quite electrical, maybe rubber.

I pulled over and checked under the hood, and saw nothing obvious. No fluids leaking, reservoirs were where they should be, oil was fine, belts looked in place.

I proceeded to drive home. Once I got home, while idling in the parking lot, I turned on the heat, immediately heard the noise, and turned it back off again. In addition, my dash lights and what not dimmed a bit, as if something was pulling on the engine pretty hard.

What might the problem be? Is there a bearing in something that might have failed?

I don't know if it matters or not, but I was driving through a light rain around 40 MPH when I first noticed the problem.

EDIT: I discovered this morning that this only happens when the defroster is on. With just the heat on, it works fine and there is no problem.

2 Answers 2


Sounds like a failing A/C compressor. Assuming the car has A/C... A/C compressor is used with the defroster to dry the air.

  • Thanks Brian, that seems to be what the problem is. My A/C quit working near the end of the summer, due to a leak in the tubes that go to the rear of the van. I had assumed the compressor wouldn't kick on, since there is no pressure of refrigerant. Is there a simple way for me to disable the compressor, so I can at least use the blower on my windshield? Pulling a fuse or something so it doesn't engage? I can't quite afford a costly a/c repair at the moment, and would rather replace the compressor next year.
    – Brad
    Nov 9, 2011 at 21:34
  • Tonight, I pulled out the a/c relay, and that seems to be preventing from the compressor turning on, and hot air blows out of the vents on the windshield. This will work well for me until I can afford a new compressor. Am I damaging anything with this method? Is there anything I am not considering?
    – Brad
    Nov 9, 2011 at 22:53
  • I suspect you'll probably be fine with that solution. I did the same thing on both of my cars when the A/C failed (and was too ridiculously expensive to repair). That's been a good 11 years for the one car and 5 or 6 for the other. So far no untoward side effects from having the relays pulled. Longer term I suspect that the contacts might corrode from being exposed to air though. Nov 10, 2011 at 13:26

That sounds like the bearings in the fan have failed, or something is caught in the fan, stopping it from turning.

I've got no idea where the heater fan would be on a Sedona, but chances are it'll be behind the dash somewhere - If you're lucky it might be on the engine bay side of the bulkhead, but if it is inside it'll be a pain to get to, and will probably involve talking half the dash apart...

  • Thanks Nick. I found out this morning that this only happens when the defroster is on. It doesn't happen when I turn on the heat. With heat only, the blower works just fine.
    – Brad
    Nov 9, 2011 at 14:34

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