dash rattle

[saraf]

Happy New year

I have a puzzling situation. When I turn the heat on to automatic in cool weather, a small flutter sound occurs behind the dash glove box. The sound stops when the fan is off. The car motor can be running or off, makes no difference. The sound does not seem to increase when the fan is sped up using the manual feature, although the sound may be drowned out by the sound the fan and air. The most puzzling part is that this does not happen all the time. I cannot get a constant set of parameters to this situation.

This sound is not affecting the car in any way.

I have thought of removing the interior panels of the car but have decided against such a foolish activity since I am not mechanically inclined. Perhaps this is just my way of having a customized Porsche. LOL

I thought perhaps someone else has experienced this situation.

[rsfeller]

Are you sure this is not more present all the time? On the right side of the car is the air temp intake sensor and it has a fan to push the air flow in. It can buzz pretty bad (bad bearings?) and I've seen them busy in other make/models pretty good too.

Shawn

[wvicary]

I would also check the fan for the cabin air temp sensor.

[saraf]

Thanks for the info Shawn

Most of the time I can start the car, parked in a warm garage, drive around outside in the cold weather, activate the heater by pushing the auto button with no strange "flutter" sound coming from behind the glove box. (the sound is not a rough bearing sound). Occasionaly the "flutter" sound will start immediately when the fan starts.

Is there anyway of looking at the interior workings of these units without to much work.

Just some thoughts

Saraf

[rsfeller]

Thanks for the info Shawn

Most of the time I can start the car, parked in a warm garage, drive around outside in the cold weather, activate the heater by pushing the auto button with no strange "flutter" sound coming from behind the glove box. (the sound is not a rough bearing sound). Occasionaly the "flutter" sound will start immediately when the fan starts.

Is there anyway of looking at the interior workings of these units without to much work.

Just some thoughts

Saraf

In regard to HVAC systems there is not much to go wrong. You have the servos that open/close the flaps, the fan motor and the air intake sensor. The only other think I can think of that may sound like a flap would be something intermitantly getting in/out fan blades. I had a leave get in my saab two years ago and come and go. Another time the bearings in the fan motor were sloppy and after making a long right turn the fan would slide on the axis and rub the side o the fan case and make a flutter sound.

I doubt the servos are to blame. The Durametric software would help with that diagnosis. Taking a part any car dash is not fo the faint of heart and usually not neded. With most cars a particular problem can be address from under or behind.

Any chance it's comeing from the main fan and heater core housing? This is a 2 hour job to open up (as well shown in Bentley) and you could monitor the fan with the top cover off.

See my write-up for some very unrelated discussion:

Additionally, I have heard temp intake sensor fans "flutter" before. They just pop out you can unhook it and run w/o to see if that may be to blame for the noise.

Shawn