Hello, have not noticed this before, but while driving SWMBOs Fabia today, the fan appears to boost to max. when selecting reverse - A/C was on, with fan set to approx. 50% - can anyone explain the reason for this?

I've not noticed this feature in my Octavia.

When selecting reverse, the action is broadcast on the CAN BUS and the HVAC system closes the air intake door so you don't inhale your own fumes as you are reversing.

Edited 8 September, 20232 yr by Crasher

Interesting, my Octavia (MY16) doesn't appear to have this feature - I assume this was introduced later.

Well I can only go back as far as 2000 in the VW Group world of motoring, and all 6, 3 VWs, 2 SEAT and 1 Audi, have all had that feature, so its been around for a while now.

Which means that mine is inoperative for some reason. Hymmm.

It used to be a permanent feature but since the arrival of complicated infotainment systems the feature might need to enable it by ticking a box somewhere in the menus so it may not actually be broken.

 

Best place to start is making sure the recirc flap is working when you press the button on the dash. Another reason might be that the noise change is not as noticeable on other models

Perhaps you are being confused by the incorrect description of it being a fan boost to maximum speed, it simply switches to recirculated cabin air, you may not hear the difference in tone on some vehicles, it would be their aim to make it indiscernible if that is a word.

 

Also if you have Climatic as I have and not Climatronic it probably isn't a feature of the simpler system, that said it does some things automatically that I did not expect so it has some intelligence.

This feature was incorportated into all systems whether climate controlled or not. I don't remember my Mk 4 golf/B5 passat having this feature but my Mk5 golf with climatic did so like back end of 2004+ is it was in VW at least.

21 hours ago, J.R. said:

Perhaps you are being confused by the incorrect description of it being a fan boost to maximum speed, it simply switches to recirculated cabin air, you may not hear the difference in tone on some vehicles, it would be their aim to make it indiscernible if that is a word.

 

Also if you have Climatic as I have and not Climatronic it probably isn't a feature of the simpler system, that said it does some things automatically that I did not expect so it has some intelligence.

There is a very pronounced increase in apparent fan noise in the Fabia, to the point that it sounds as if the fan is switching to max. whereas no change at all in the Octavia.

I will recheck the recirc. flaps, but reasonably sure they are ok.

Both Octavia and Fabia have 2-zone climatronic. 

Are your reversing lights working?

On 10/09/2023 at 13:47, Warrior193 said:

Interesting, my Octavia (MY16) doesn't appear to have this feature - I assume this was introduced later.

my mk2 octavia, 2013, among the last out of the factory, does this..

it does make it sound louder but its just the movement of the airflow source when the baffle moves.

 

52 minutes ago, Breezy_Pete said:

Are your reversing lights working?

Good call!

Just checked - working OK. I thought that was all ok as the rear wiper and rear sensors were operating normally when reverse selected.