Little noise won't go away

[micklepuss]

Hi Guys, I have a noise that has just started in the last weeks, it comes from the right fender just infront of the door hinge. When you start the car cold or hot it sounds like a vibration (higher pitch hum) which fades away after 15 - 20 seconds but then if you tap on the gas pedel the vibration revs up and then stops. this also happens on my 900 86 8v who's 20 this year.

I think it's coming from the pollen canister but not really sure

[Licence]

Is it the vacumm flask thing (between the outer and inner wing on the same side as the pollen filter - white with vanes round it) leaking as it tries to create a vacumm on start up?

[Jim Mesthene]

The noise you describe is usually coming from the vacuum tank check valve. Usually, they make noise because there is a vacuum leak in the ventilaion controls. The most common places for leaks are at the back of the distribution valve and at the defrost motors under the speakers.

[micklepuss]

Hi Licence, you've got it right on the nail but the sound doesn't sound like air leaking out like when you shut down the mode switch for air direction, it soundz like a vibration. I will check this modual to see if leaking.

Thanks Heaps for your input