I'd pull the 30a one on the battery as the cabin one does a few other things too from memory. Or disconnect the multiplug

Okey doke. Will do in the morning, or afternoon, depending on how this evening goes...

Made no difference, unfortunately.

Four years later...

I think I finally got to the bottom of this.  A leak of air into the PCV valve was fixed, for reasons related to engine running/faults; and all of a sudden the brake servo is behaving like it did when we first got the car more than 8 years ago.

 

I might make a little video later, but the diagnostic for this fault is to stick a finger over the pressure equalising port of the PCV valve while the engine is idling, fully warmed up.  There should be no effect if all is well with the valve.

 

If the diaphragm in the valve is leaking, things will be different.

Here's a photo of the valve cap/diaphragm/spring (upside down compared to how it is fitted on the 1.2 engines) with pressure equalising port marked:

 

I've noticed that my brake pedal drops ever so slightly when I have it pressed and turn off the A/C. I didn't notice the same thing happening in any of my other VAG cars. I wonder if somebody around here with a healthy car and A/C can check if that's normal or if that is indication of something amiss. Servo hoses seem healthy, pressure equalizing port in the PCV seems to be working as it should. TIA.

Is that a Bahco socket set case that the cap is photographed on?

 

If so you are an even wiser man than I thought

Yes @J.R. that's the 3/8" set, I also have a 1/2" and a 1/4" set.

I can report nothing but great service from them, with the exception that using the back of the 3/8" ratchet handle as a hammer may result in breaking the forwards/backwards ratcheting selector lever. Not sure which wise man might have done that, as I'm the only one that ever uses the set? 😑

@Wino

 

This is the one that I keep in the boot at all times:

 

https://www.ffx.co.uk/tools/product/Bahco-S138-7314150195022-Socket-Set-Of-138-Metric-1-4In-3-8In--1-2

 

A present that I bought myself even though I am not worthy!

 

Its so comprehensive and such good quality that I rarely get out my proper mechanics tools, I bought the set because i am usually in another country to my workshop.

 

It really was a good buy, I bought it from them because their delivery cost to France was very reasonable for such a heavy item.

Now why did you have to go and show me that?! Aaaaarrrrrgggghhhhh!!! 

Looks damn handy...Incredible value for money too considering what you get.

 

@juanse_2691, I will experiment tomorrow on one or both cars that I am near to see if I can replicate what you experience.

 

Re the toolkit, its removed for the photos but there is actually a hinged rigid plastic divider that seperates the tools in the upper lid from those in the bottom, it holds everything tightly in place when its closed, it is secured in the top part and can be released or removed, it also has a pictorial plan of where everything is and the sizes.

 

The spanners lift out as a complete set in their own carry holder.

 

I bought it for the mixture of 1/4", 3/8" and 1/2" drive normal and deep sockets and also for the crowsfoot spanners which I have yet to use, it all seems very robust & high quality especially the box, its hinges and catches which can all be unscrewed and replaced.