Palatinux

After some maintenance on the electronics on my old Fabia, I forgot to place back the connector of the blue clutch pedal switch (see image below which is borrowed from this forum). The function of this switch is for the car to notice when the clutch pedal is pressed in, and then the engine quickly reduces it's RPM to be more in line with the RPM of the gearbox. When the switch is faulty, the car thinks you are using your clutch every time you release the gas, which causes a shocking / shaking experience while driving. The car doesn't produce any warnings or fault codes, so those who have a similar problem could check this switch and its wiring.

Replaced the flap motor in feb 2023 with the pretty good quality 'Saborway Air Heater Servo Recirculation Flap Motor' https://nl.aliexpress.com/item/1005004675833081.html and is still running strong in nov 2023. This new flap motor has a metal internal bolt for the large cog wheel instead of a plastic one on the original, which is the main point of failure. This version doesn't slide the cog in or out and simple stops at the ends and doesn't make any noise.

Everything is reinstalled into the car and the hypothesis became a fact. It operates 'smoothly' and the re-circulation flap closes better than before. Especially lining up the gears according to the manual here above, was a big challenge. Shaky modus operandi video attached. When you turn on the ignition, it feeds power to fuse 12. The J251 then drives the V154 for 10 secs until the flaps are in 'fresh air' and the gear slips. I don't see a connection on the J251 in the schematics that always applies 12V to the unit in order to remember it's current state nor I can find proof that the J251 is able to store it's current position into it's controller. But this doesn't solve the mystery why I only heard the V154 for the first time while on contact, after cleaning the flaps and blower a few weeks ago. VID_20211217_180811(1).mp4

So it just shows 'Open' or 'Closed' in the measurement blocks in module 08 "Climate Control" > group 005 > block 1 (actual value), block 2 (desired value), block 3 (set to fresh air), block 4 (set to recirculate) ? But it all might depend on the make/model, since mass-production of the V154 unit (with unused features) and selling it for 1000% of the production price is more important to VAG 🤔 Since there is a lack detail, I should indeed be careful with my hypothesis until proven in the car. But it still doesn't explain why I heard the V154 for the first time after so many years and after cleaning the blower/flaps while putting the contact on. I always wait at least until the self-diagnosis is completed before I start the engine. So best advise in this situation, make a video first before taking it apart. 😳

The potentiometer in the V154, is called G143 in the repair manual I have about the air conditioning. Mine V154 doesn't switch positions when selecting reverse, but I guess all activate when turning on the contact and it definitely causes unnecessary wear and tear I've seen on the scratches in the sliding/skipping part of the V154. I guess the G143 is only used while airco or climatic is activated to regulate the V154.

If you have a climatecontrol (or AC), it might throw errors at module 08 in VAGCOM if the potmeter is dirty, as seen here: Newer model V154 with ac: Some modus operandi, but this one is stuck: The clicking sound you hear at 0:50/0:51 sec, means the cog is in it's end position and something is stuck if you hear it more than once.

I didn't have time yet to get on all fours and sprain something else that is old and brittle testing it in the car under the dashboard, but I found this out while testing the unit at home: My car doesn't have AC or climatronic, so it doesn't require a POT meter to be present in the V154 unit to know it's current position. The same unit seems to be used or still be used in many VAG cars, so this might be helpful to others. if you have trouble with the ventilation loosing power, sucking up air from the passenger foot-well when recirc is disabled, you hear clicking or other noises from the device or when the recirc button turn's of pretty quickly, this unit might be the cause. I my situation, there is no active monitoring or control over the V154 by any modules in the car. When your turn the contact on, it always drives the motor for 10 secs to the 'fresh intake' position, and when you press the 're-circulation', it reverses the polarity on the motor and does the same the other way round. It even does this when the module is not attached. When they gears are lined up as described here above after the 're-circulation' position is met, it should line up the two tabs marked in green in the picture or on the other side. When the cog is moved towards position 'red arrow 1' and the two tabs meet, the cog is pushed outwards until it runs free (red arrow 2). Same goes for blue arrow 1 and 2 , but that is the other way round. If you hear clicking, noise or if the motor has a hard time turning or sliding the cog to position '2', it would need cleaning and lubrication of the motor/gears and especially where the large cog slides in and out of the unit/last gear. The large cog is held to the unit by tabs inside the hole in the last gear, which broke off in my situation, but that doesn't hurt any functioning when installed... I think. If the sliding part is dirty or doesn't have any lubrication, it may finally jam the whole system or burn out the motor inside the V154. Note that a new V154 costs around 125 to 150 euro. I'll be back if I managed to install it back completely into the car.

Before I forget, some extra reference from the manual, but not sure if it fully applies to my V154 unit / 6Q1907511.

That is completely true sepulchrave, almost all polymers are subject to heat/UV aging , especially ABS. It then loses strength, flexibility and break easily when stressed. A connector under the dashboard and engine bay break faster than when it is situated under the car. Just buy a new car, let it bake in a hot summer day and smell the toxic fumes inside the car. Plastic fantastic. 😁 One of the reason why I spray a mixture of soft soap and water in the engine bay and under the car once a year.

Thank you Pete, that is a very plausible explanation. Because of this design, it may be a good reason why the cog broke of internally even when I carefully cleaned the flaps; to much stress already in 21 years. Before I removed the V154, everything worked perfectly without any strange sounds. The only difference was that I now heard it engaging every time when I turned on the contact. So by your old posts and other video's on YouTube, I expected to find a dirty pot in the V154 that would be issue... which was not there. The motor normally draws 16ma> 20ma. But when you hold the cogs down, it increases to 30ma > 40ma. So I try to do the same next week in the car and see if it stops a.s.a.p. Some pics attached for extra info and will update my findings later on.

Dear members, its been a while and wish you a good weekend. After carefully cleaning the leaves and dirt from the blower and fresh/recirculated air flaps, the large cog on the outside of the air flap motor doesn't stay in position anymore and has broken internally. This can easily be fixed by applying glue, but I noticed that the motor is now engaged every time I turn on the contact no matter what the last position was. The fresh/recirculated button doesn't light up in the meantime, but all still works normally when pressed. Despite a lot of searching, I cannot find a possible reason why it activates by itself or why I 'forgets' its last position. Hopefully some of you have enough experience on this subject. I've attached the right schematic for my car.