My wife's 2000 V70 (42,000 miles) has a strange 'knocking' noise from the dash when the A/C is on. It almost sounds like there is a mouse inside the dash running around! It comes and goes (unable to duplicate it for the dealership) at random. I know it is electrical because the noise stops when the key is pulled (or the fan is manually turned off). It is loud enough to be heard while on the freeway.

Could it be a 'flapper' (diverter for the air) for the A/C system going out of control? Any other ideas?

Thanks in advance.

I have the same phenomenon with my 98 V70 T5M. It emanates from just to the right of the radio. It sounds like a vinyl-on-vinyl squeek which might be caused by car motion, but it persists even when sitting in the driveway. And sometimes it sounds like the knocking noise that you described. It stops when I shut down the Climate Control System. I strongly suspect that it is defective vent duct continuously cycling open and closed.
I am hoping someone will have experienced and solved the same problem. I am resigned to eventually doing an "open and inspect", but I hope someone can save us too much extra work.
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Dave in Virginia; 98 V70 T5(M); 98 V70; 88 245 DL; 67 MGB

That is exactly what it sounds like.... vinyl being rubbed on vinyl. At first, I thought it was something in the glove box, or two dash panels creaking... but then it is not consistent with any movement of the vehicle. It is related to the A/C system, and my best guess is that the noise is from a defective air diverter (or flapper) that is cycling on and off. I hope (this week) to get the dealer to hear it - and fix it under warranty. Let me know if you want me to e-mail you with the diagnosis.

Yes, please let the Brickboard (and me) know the outcome with the dealer. If we two have had the problem, it is likely that others have had it as well, even if they haven't posted to this thread.

So, it is good form to close out a problem on the Board so that it will not have to be asked and answered again. It may even be selected for the archives. I look forward to your dealer's diagnosis soon. That little flapper must be wearing itself out working so hard.


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Dave in Virginia; 98 V70 T5(M); 98 V70; 88 245 DL; 67 MGB

I have a 98 V70XC, and I'm experiencing the same noise from the dash. It stops when I manually turn the climate control off. Has someone posted the outcome of the dealer's diagnosis? Thanks!

expect it is blower fan. If so should be noisey with ac or heat or just fan

Probably got something caught in the squirrel cage

The noise is identical whether or not the fan is on high or low. My first thought was that something had been sucked in, but then it would change pitch (or rate) with the fan. The noise is completely random, and sounds more like a knock.