HVAC distribution flaps failing

[amiran]

Hi everyone,

I recently bought a 2016 Seat Leon ST, and I've noticed an issue with the climate control.

When the A/C is on (whether it's blowing cold or hot air), I'm getting very little airflow from the two front centre vents. I'm also barely getting any airflow from the footwell vents.

Here's what I've noticed so far:

• The side dashboard vents work perfectly.
• The rear vents also seem to work fine.
• The windscreen/defrost vents do blow air, but the airflow is quite weak unless I turn the fan speed up significantly.

Tests I've already done​

• Performed the air flap calibration through the climate control. I could hear the flap motors moving, but unfortunately nothing changed.
• Scanned the car with VCDS, which returned the following fault codes:

4 Faults Found:

328964 - Motor for Front Air Distribution Flap
B1091 71 [00001000] - Actuator Stuck

328965 - Motor for Front Air Distribution Flap
B1091 54 [00001001] - Missing Calibration / Basic Setting

329476 - Motor for Fresh Air / Recirculated Air Flap
B108B 71 [00001001] - Actuator Stuck

329477 - Motor for Fresh Air / Recirculated Air Flap
B108B 54 [00001001] - Missing Calibration / Basic Setting
I'm hoping to diagnose and repair this myself, as I'd like to learn more about the car and enjoy doing my own maintenance whenever possible.

Before I start replacing parts, are there any additional tests I can perform using VCDS to determine whether:

• the flap motors have actually failed,
• the flaps are physically jammed or obstructed,
• or if there's another issue causing these fault codes?

If it does turn out that the motors need replacing, I'd really appreciate:

• any guides or tutorials on replacing them,
• any tips from someone who's done the job before,
• and, if possible, the correct part numbers for my car.

Thanks in advance for any advice!

P.S. This is my first thread on this forum, so apologies if I've posted it in the wrong section or missed any forum etiquette.

 

[RUM4MO]

In the past, I've used VCDS to perform "BASIC SETTINGS" - that is a test or sequence that demands each flap motor to be moved to one end, that voltage is memorised, then moved to the other end stop, and again that voltage is memorised. The controller will then use these stored values for positional control of these flap motors.

You've done the correct thing as in the way you have posted this, so no problems there!

Good luck with fixing this issue, this problem can end up happening with any VW Group marque car from at least 1998 - and is probably still happening. Usually it is caused by us just leaving the HVAC controls set at the same settings for ever, these flap motors have a potentiometer fitted to them so that they can be controlled by the controller and these potentiometers voltage is used to control and confirm the position of the flap. Over time the track on the potentiometer gets dirty or does not conduct as well as it initially did as does the contact "finger" that presses down onto the potentiometer track - so control gets lost, this usually starts with "hunting" as the controller tries to regain control, and this normally means that you hearing clunking of knocking noises from the flap. Demanding that flap motor moves to each end stop many many times can sometimes clean the track up enough for control to get regained - for a period in time. Stuck actuators might just be due to something ending up in its path and so limiting its movement - only one way to find out I suppose. The other thing that has been happening to some cars is, the actuator forces its drive cogs apart - or at least forces the actuator case open, which can also leave the actuator stuck.

All good fun - if you can get your hands into where they "live"!

 

[amiran]

In the past, I've used VCDS to perform "BASIC SETTINGS" - that is a test or sequence that demands each flap motor to be moved to one end, that voltage is memorised, then moved to the other end stop, and again that voltage is memorised. The controller will then use these stored values for positional control of these flap motors.

You've done the correct thing as in the way you have posted this, so no problems there!

Good luck with fixing this issue, this problem can end up happening with any VW Group marque car from at least 1998 - and is probably still happening. Usually it is caused by us just leaving the HVAC controls set at the same settings for ever, these flap motors have a potentiometer fitted to them so that they can be controlled by the controller and these potentiometers voltage is used to control and confirm the position of the flap. Over time the track on the potentiometer gets dirty or does not conduct as well as it initially did as does the contact "finger" that presses down onto the potentiometer track - so control gets lost, this usually starts with "hunting" as the controller tries to regain control, and this normally means that you hearing clunking of knocking noises from the flap. Demanding that flap motor moves to each end stop many many times can sometimes clean the track up enough for control to get regained - for a period in time. Stuck actuators might just be due to something ending up in its path and so limiting its movement - only one way to find out I suppose. The other thing that has been happening to some cars is, the actuator forces its drive cogs apart - or at least forces the actuator case open, which can also leave the actuator stuck.

All good fun - if you can get your hands into where they "live"!

This weekend I will take a look and clean them properly. I will update you on how it will go