Defrost Rattle

[Mike1767]

After making the tough decision that my 89 740 wagon was no longer worth the money needed for new parts I have updated to an 06 XC70. After 2 weeks, I am absolutely loving the car. Just noticed last night that there is a rattle coming from the passenger side dash area whenever the car is in motion and the heat is set to defrost the windshield. Any ideas as to what it might be?

[howardc64]

After making the tough decision that my 89 740 wagon was no longer worth the money needed for new parts I have updated to an 06 XC70. After 2 weeks, I am absolutely loving the car. Just noticed last night that there is a rattle coming from the passenger side dash area whenever the car is in motion and the heat is set to defrost the windshield. Any ideas as to what it might be?

I think several vents have doors that open and close depending on the climate control operation. They have motors inside as well as plastic linkages that activates these doors.

One door that has a few linkage on it is the fresh air door that determines fresh outside air or recirc interior air. I think this door closes when you go into windshield defrost or AC. Windshield defrost and AC are related because AC unit is what pulls the moisture out of your cabin during defrosting. The fresh air door is just inside the passenger dash behind+above the glove compartment. It is fairly tight to maneuver your hand in there and the glove compartment is a little tricky to know how to pull off.

[RockitShip]

Meh... my fan is noisy at certain speeds. Are you sure it isn't the fan?
Someone used generous amounts of felt on my Audi LOL!!! I can attest
to using felt... many have done it to quiet their squeaks & rattles.

[Mike1767]

Thanks guys, I'll have my wife drive me around and try to figure out exactly where it's coming from. Hoping that it's more of a felt issue than an under the dash issue. Will let you know.

[Mike1767]

So on further inspection and finally remembering what exactly the sound reminded me of (worn out computer fans) I'm pretty sure it's a fan issue. Thanks for he help.