thanks for the tip ! will give it a go , but don't know what actuates the heaters or at what temperature or how I will notice if they actuate !

I've never understood the logic of heated washer jets anyway.
Assuming you have the correct mixture in your washer tank for the temperature why would just the jets freeze up?

I'm sure there are some (maybe rare) meteorological conditions where it helps..... :Confused:

Has someone tried spraying/injecting some de-scaling stuff in them?

Something like GroheClean or perhaps white spirit.

So it'll dissolve the scale into pieces that will be washed away next time washers activated.

I have a vague recollection of reading (or seeing a circuit diagram confirming) that they are on all the time (with ignition)!
I do remember measuring the resistance a while ago to check what current they would draw, hence wattage. It wasn't much.
(Just measured a non-Audi pair I have to hand, about 45ohms so around 3W each.)

Resurrecting a very old thread as my MOT is due and washer jets are a bit feeble......
Decided to try descaler first (HG stuff as noted above, neat) but in situ. Weather isn't conducive to dismantling! :tuttut:

First I just applied a few drops with a small brush, observed fizzing so repeated a few times over an hour or so.

Then I used a small syringe, loaded with a couple of ml of descaler, and pumped it gently in and out of each nozzle in turn. It obviously squirted out the other nozzle in each pair, along with fizzy bubbles.

Again repeated a few times until it ceased fizzing and they're now working well. Ideally need a bit of adjustment but are fine for MOT purposes. +++

As implied above, I think the heated nozzles dry out the nozzles excessively causing them to block.