Hi, I change the LEDs on my heater controller, and those 2 pieces fell during disassembly. I can't figure out how to put them back, and it seems they serve no function as I can still control fan speed without these.

If anyone knows.

 

Thanks

They are the switch contacts for the fan speed switch.They both need puting back into the rear of the knob.Then the knob should carefully put back into the middle position where it came from. 

Ok, make sense that they are contacts since they are made from metal. From what I can see, I was right thinking that they are going into the back of the knob, but I looked at it for a long time and still can't figure out which way the switches go. By the look of it, the switches can't stick out of the knob because they'll hit the white housing. The larger plastic part of the switch can't fit in the hole behind the knob. For me, the part of the switch circled in red in going behind the knob where I circled in red, but it does not fit properly so I guess I may be wrong.

They are contacts that make/break circuits as the vent control knob is moved to different positions, and possibly the temperature control too.

There are only pairs of pads on the board (yellow rectangles) for two to be fitted on this variant - from a 9N Polo - but positions in the white  plastic moulding for two others associated with the temperature control knob.

Only the one fitted (in one of the green rectangles) as shown in this case, but I have taken this unit apart several times so the other may have dropped out and got lost/misplaced.

 

The one here possibly senses when the knob is pointing at windscreen vents to do some A/C-related function, not sure what the other would do on this one if fitted.

I think if there was one on the temperature control knob it would indicate 'max temp demanded' to the stuff controlling a PTC auxiliary electric heater, only fitted to diesel Fabias and only then as an option, ISTR.

Have a look where there are similar pairs of gold-plated pads on your board and hope that there aren't too many choices to confuse matters!

 

 

 

 

Thanks for your detailed answer @Wino, I took a video of the board before desoldering the LEDs, and it seems like my board is the same as yours. I only have 2 pads for the 2 switches.

I think that the previous owner already took it apart because the 2 switches fell when I removed the fan speed knob. No idea how that would happen otherwise.

 

Here's the video of the board.

 

I'll keep you updated when I'll take it apart, it's a pain to remove the entire lower part of the dash just to get this module out.

I would think the black plastic pegs on the contacts fit into the rear of the knob.The 4 non movable  contact pads on the square black plastic part are the out connections to the wiring.  THe large silver contact pad in the black plastic part is therefore connected by the contacts (which in your case have fallen out) to the 4 contacts in turn depending on the switch position. This switch would be known as  a 1 pole 4-way out switch.

I managed to remove the module without taking every part of the dashboard out. My fingers hurt from trying to remove the 2 black connectors, in such a tight space, thanks to the little tabs that are so hard to release. Anyway, I opened it and the 2 switches sits where @Wino pointed on his picture. They definitely don't fit behind the knob. The mecanism that tells which fan speed is selected is the copper part we can see on the black plastic thing. The knob is just here to turn this copper plate. Now that the 2 switches are in place, the vent control knob feel a little different and stays better when in position. I still don't know what they are for, but they're back in place.

 

For Fabia owners, I made a hole at the bottom of where the headunit seat to get access to the back of the module. This way, you can release the module from the front without taking the whole dashboard out.

 

Anyway thank you for your answers.