2001 V70 T5 Odd sound from behind pass dash

mdewalle · Post by **mdewalle** » 20 Oct 2014, 06:40

I'm getting an odd sound coming from behind the dash on the passenger side. It sounds like a servo motor turning on/off for about 1-2 sec intervals (or maybe a relay?). I only hear it when speed goes over about 20 mph. It will do it a couple times and then it may be quiet for a while. If I'm in the city going from traffic light to traffic light, it will do it each time I speed up over 20 mph.

I don't think its the CD player, because it still does it with no CD in there or with the radio on. I've driven with the glove box open and the sound does not seem louder. I don't use the "Auto" setting on the air vents, so I don't think its automatically adjusting the valves for the air flow (besides, why would it do that each time I go over 20 mph?).

No codes, and everything seems to work as normal.

- marc

Post by **JRL** » 20 Oct 2014, 08:58

Does it do it with the AC/heater blower switch turned to full off?

mdewalle · Post by **mdewalle** » 20 Oct 2014, 21:06

Yes, I should have said that the fan is turned to off (and I don't use "Auto"mode).

hermechanic · Post by **hermechanic** » 21 Oct 2014, 09:10

What is the air recirculation switch set for? Does that make a difference? ~Steve

Post by **jimmy57** » 21 Oct 2014, 14:15

+1 on that.
The recirc motor can be active when topped and when you drive off again at some temps.

I know of several 99-04 P2's with damper motors that have the Chihuahua scratching at the door noise that have no issues other than the noise.

mdewalle · Post by **mdewalle** » 22 Oct 2014, 19:16

I will test that tomorrow to see if that matters.

- marc

hermechanic wrote:What is the air recirculation switch set for? Does that make a difference? ~Steve

mdewalle · Post by **mdewalle** » 22 Oct 2014, 19:18

What do you mean by "topped"?

This sound "Chihuahua scratching at the door" actually kind of describes it...

jimmy57 wrote:+1 on that.
The recirc motor can be active when topped and when you drive off again at some temps.

I know of several 99-04 P2's with damper motors that have the Chihuahua scratching at the door noise that have no issues other than the noise.

hermechanic · Post by **hermechanic** » 22 Oct 2014, 19:59

typo? topped = stopped?

mdewalle · Post by **mdewalle** » 22 Oct 2014, 20:18

Yeah, he probably meant stopped. I'm gonna test with having it on and off tomorrow.

hermechanic wrote:typo? topped = stopped?

Post by **jimmy57** » 22 Oct 2014, 21:23

Stopped. 0 MPH.

Volvo likes dog phenomena. The cooling fan kicking on and dropping engine idle speed on 92-95 740/940 would cause the engine to shake and vibrate the car for a few seconds. Volvo called it "wet dog syndrome".
The damper motors on P1's could get stuck in a cyclic operation and they made a noise that sounded like a dog barking slowly and was named "barking dog sound". I figured I'd not deviate from the canine theme.