Rumbling Noise From Under Dash

[PhilT]

I have an intermittant rumbling noise like a bearing rubbing or something catching when the ignition is on (but not the engine running). It is coming from under the dash in the centre but sounds as if it is in the passenger compartment rather than the engine bay. It is not the heater fan. Any ideas anyone?

[big_kev]

one of the motor's for the heater flaps, maybe ?

 

Probably the hot/cold one..

[Mirez]

Almost certainly as suggested, the flap motor and the temperature motor are both "stepper" motors - ie they turn in increments, albeit quickly. When turning they make a rumbling noise due to the On/Off phases of the stepper. The SATC climate panel has a startup sequence which moves the motors through a full cycle as a test, I can only imagine there is also some kind of testing happening with the non SATC version.... if you leave it for, say a minute, will the noise stop?

[PhilT]

yes, that's it exactly, and it is very occasional so I won't worry about it. Thanks.