Strange new noise

[Fille]

When i turn on the ignition on my car I have lately noticed a new noise. It comes either from the engine compartment or the heater assembly. It sounds as if a flap is closed and then opened again. A bit like the headlight alignment that goeas up and down, but this is louder and closer to the passenger compartment.
... Are the VIS motors tested on every startup? and if they suddenly are noisier than before I suppose it can mean no good?

[Fille]

It's a bit like thump-thump a split second after ignition is turned on. Any ideas, anyone?

[stocktake]

Not going to be VIS motors, possibly heater flaps?

[Simon]

The air recirculation vent automatically opens when the ignition is turned on and then closes when you turn the ignition off. It is quite audible on my car but others have reported not really hearing it at all. Could it be this that you are hearing?


NB: The operation of the auto opening/closing is dependent on the external and internal cabin temperatures but it gets complicated so I wont go into detail unless asked

[Fille]

That sounds possible, although i did try the recirculation button a couple of times to see (hear) if it would emit any noise but I could'nt hear anything then... Will investigate further on sunday when I have the car indoors (to try to solve my traction control problem ;-))

[Jamie]

Originally Posted by Simon

The air recirculation vent automatically opens when the ignition is turned on and then closes when you turn the ignition off. It is quite audible on my car but others have reported not really hearing it at all. Could it be this that you are hearing?


NB: The operation of the auto opening/closing is dependent on the external and internal cabin temperatures but it gets complicated so I wont go into detail unless asked

Spot on there Simon...this noise (Flump!) is the flap that you can see in the heater system when you change the pollen filter, as you turn on the ignition it repositions...now a word of Caution....if you used one of those air conditioning airosoles (bombs) they make the flap sticky which makes the noise much loader as the flap suddenly comes unstuck and wacks open.

I cleaned the flap on mine to stop this happeneing...it started after using a perfumed airconditioning bomb....it only happens after the car has been sat for a while...so it wont do it once youve used the car

[Fille]

I have found the source of the noise - it is the traction control actuator. On turning on the ignition, it does a full cycle test, ie it closes the secodary throttle and then opens it again. However, the noise is new, and as my t/c has developed an intermittent fault so I suspect these two are related... So nothing to do then but call the garage again...