In the past 6 months my Volvo XC70 has had a very loud, high-pitched whine coming from the center part of the dash, perhaps in the area of the heater controls or maybe the radio. This has happened ONLY while driving in heavy rain between 50 and 60 mph. My Volvo XC70 has about 92,000 miles on it.

The last time it happened the noise stopped after only 30 seconds, the first time it happened it took about 5 minutes to stop. I've tried slowing down, turning the radio on/off, adjusting the fan speed, temperature, a/c control, air recirculation, etc. --- but nothing changes the tone or duration of the noise. It just stops by itself.

It doesn't seem to affect the car's performance, but it's very annoying and distracting. Does anyone have a idea of what's causing it and how to fix the problem?

My wife`s `03 XC70 will emit a high frequency "whine" when we have the fan on "high". Stops when we lower the fan speed so it`s likely the bearings in the fan. Apparently, you`ve tried that solution without success.
Hmm.......hope you find the issue & I`ll look forward to reading further.
Rich

Rich,
Thanks for your quick response. Yes, I did try turning off the fan and changing its speed but that didn't stop the noise. Volvos sure have some strange electrical issues!

Kind of a long shot, but did you try turning the wipers off to see if that made a change?

Charley

Didn't think of turning off the wipers. I'll try that next time. Thx.

Thanks for your responses.

Well. It happened again. This time there was no snow, but we hit heavy rain in Ohio. Had been raining for a day (driving through Michigan) and used a/c, wipers, etc. all day. No strange noises. Then the rain got heavy and the high pitched noise began again. I turned off the a/c and fan, turned off the wipers and turned off the radio. Noise continued. When the rain tapered off a bit the noise stopped.

No noise for another 50 miles or so until the rain got heavy again. Then it continued for many miles until the rain slowed down. Again, I tried turning off/on the a/c and fan and the wipers. That made no effect on the noise. I also slowed down, changed speed...that didn't stop the noise either.

Anyone have an idea what this is? Otherwise the Volvo XC70 runs great, 94,000 miles, 26-27mpg for 1,000 highway miles- 22-24 city driving . Doesn't use oil.

????

I am not convinced it is the dash as there are no motors there, except the blower.

Could it be a slipping serpentine belt? Using a spray bottle, spray the belt while the engine is running and check that.
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My back feels better when I sit in a Volvo seat

Klaus,

Thanks. I just tried spraying the serpentine belt with water. Engine is at operating temperature. No unusual noise. Eventually sprayed/poured about 1 quart of water. The only ting I noticed was the a/c compressor clutch cycles on about every 10-12 seconds then releases. (Is that normal?). But, the a/c isn't making any noise and I've experienced the noise even after turning off the a/c.

I haven't been under the car: is there a place the belt runs near that could collect a few inches of water causing the belt runs through it in a heavy rain and causing the noise...rather than just the spray from up top like I did?

Any other ideas...this is a 'good' one. And, I did check- there aren't any critters living in the engine compartment.

Thanks again.

RubyXC

AC sounds normal.

Rats, regarding water on belt. No, water cannot pool in the belt area.

You need to find another thunderstorm and bring along a better set of ears, mine are shot. Go as slow as you can and lower the windows slightly to see if the noise is coming from the right or left side of the car.

Oh, trip the switch to recirculate the cabin air while you turn off the blower, radio, AC, and wipers.
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My back feels better when I sit in a Volvo seat

Klaus,
Thanks again. I had another set of ears but she was complaining about the screeching noise!!!
I'll try the recirculation button and slowing down as much as I can...on the highway it's tough to do. By the way...- what would slowing down tell us?
Waiting for the rain.
RubyXC

Slowing down helps keep the rain from coming in the windows!! I still suspect that the noise is coming from the engine comaprtment - how old is the serpentine belt? And the splash guard is still attached under the engine, right?

Is the noise is extremely loud?
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My back feels better when I sit in a Volvo seat

No one has mentioned the exhaust hitting the drive shaft. When it rains or snows, water splashes on the hot exhaust system, causing it to flex into the drive shaft that connects to the rear axle. When the system dries and heats back up, it flexes away from the shaft. Simple test is visual inspection of the drive shaft. There will be a wear mark where the muffler touches. This noise can sound like it's coming from the dash.

Thank you Bob. Good point and easy to check for ring around the prop shaft.
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My back feels better when I sit in a Volvo seat

OK Bob and Klaus.

Tomorrow in the daylight, with my fingers crossed, I'm crawling under my XC70 to look for an engine splash guard and for ring-around-the-driveshaft.

Thanks

I crawled under the car and it has all splash guards in place. I couldn't see the drive shaft- couldn't fit that far under (!) and I don't have a lift, so i will have to wait till have an oil change to see it there's anything rubbing on the drive shaft.