Occasional chirping/scraping noise in front, center vent?

[fingersmazda]

If I have the center vent button pressed on the climate control (i.e., the face level air-vents) and the climate control on a medium setting, I'll hear an occasional and infrequent chirp or scraping noise from behind the center vents. Sounds like a valve or flap opening and closing and scraping against something.

Everything works fine, it's just a nuisance.

Anybody have similar experience or insights?

Thanks in advance.

[COLO740iSport]

Could be the squirrel cage. Mine makes noise sometimes. Not looking forward to replacing that in the future. I think you have to take the whole dash apart.

Rocky Mountain 2000 740i Sport

[motion]

+1 on the squirrel cage bearings. Have you tried changing fan speeds to see if it changes?
OFF Thread I've often wonder why they contiune to use oil inpregated bronze bearings instead of sealed ball bearings? Maybe because the brushes last just as long. I just changed my blower in my e36 205k I guess I can't complain $75 for a new one.

[fingersmazda]

Thank you both.

I don't know what the squirrel cage is: Blower motor? Or just blower motor area, generally? I'm not familiar.

I looked at the dash removal DIY on E38.org. Dash doesn't look too bad. But, then once it's off, which bearings are you referring?

Thanks again. Fun!

EDIT: I've not tried different fan speeds. I tend to always have around low-medium. If I try different fan speeds, what am I looking for ?

[purplecty]

Mine does this on low to medium speeds as well. High speeds i dont heat it at all...

[motion]

The blower motor comes as a unit some have removable fan wheels some don't. You listening to see if the noise goes away. I can saftely say that changing the blower motor is not something you want unless you have to, you are correct the dash is but only part of the fun that awaits, speaking from experience you should pray that everything works once it's all back together. I'd turn the stero up and drown out the chirp.

[Miss BimmerLV]

Goodness Gracious!!!!!......Taking out the heater core and fan blower and all that is soooooooooooooooooooooooooo time consuming. Its REALLY easy... just time consuming.

Ask me how I know !

http://i43.tinypic.com/2zpquef.jpg

[COLO740iSport]

http://i43.tinypic.com/2zpquef.jpg[/quote]

:eek2 WOW! that looks like ALOT of work!

[fingersmazda]

http://i43.tinypic.com/2zpquef.jpg[/QUOTE]

The sound, to me, seems like it would be one of those flaps/valves (where the hand is in the picture), scraping when it opens/closes. I think it opens/closes to modulate the car temperature (maybe why it's heard more on low fan speeds; not so much temp moderation at high speeds).

Wonder if I could just pull the dash (the easy part), and clean/lube the flaps/valves... ??

[novasol]

Mine does this and it drives me crazy sometimes. Here's the service bulletin that applies. Yours is a 2000 though so it should have the updated IHKA and stepper motors..you may be looking at a different issue.



SUBJECT: Air Stratification Stepper Motors Noisy in E38 Vehicles
MODEL: 7 Series (E38) produced up to May of 1998
Complaint: Clicking noise can be heard from the area of the center vents during driving. The noise is especially pronounced when the stratified air wheel is adjusted (radio is turned off and blower speed is selected to low setting).
Cause: The stepper motors for air stratification are activated too frequently due to incorrect IHKA programming.
Correction: On a customer complaint basis only, replace the IHKA Control Module with one incorporating improved software (version SW 13.0) for stepper motor activation (P/N 64 11 8 385 592), and also replace the two stratification stepper motors (P/N 64 11 8 391 378 and P/N 64 11 8 391 377).
The improved IHKA Control Modules were phased into series production in May of 1998.
Note: The IHKA control module must be ordered using the last 7 digits of the VIN as the purchase order number.
Due to limited supply, you should not use these control modules for the stocking purposes.