Why wont my karcher window vac switch on even after a full charge any ideas ?

Check the hoses for clogs due carpet fibers.

Might need new batteries.Hope this helps

If you contact one of the Karcher Centers ( details are on Karcher.co.uk website) they may be able to help.
regards Gary

Have you tried to take it all apart just a small bit of rubbish will stop it from working.

Hi. I've just bought the karcher window vac wv50 & am having the same problem finding the serial No. I presume you want to register your product for the guarantee to be valid. I went online Karcher.co.uk & registered mine. You will note that when doing so it does not ask for a serial number but a model No. This is found on the side of box you got the item in (mine is just above the barcode) & it reads something like; 1.633-113.0. Hope you still have the box!

That Model of Shop vac often has on/off switch failure.

I had the same problem and I let the battery run down to stop it cycling on and off. My husband investigated it and found that there is a fault with the on board battery charge sensing circuit. (when the charge is about 10 to 15 % remaining the onboard ic controller cycles the unit on and off, irrespective of the switch. He checked it by cutting wires to the switch and it still cycled off and on so the switch was not faulty.
He put it all back together and said to charge it before it gets too low. If it cycles on and off it probably needs a re charge at that point.
Unfortunately there is no battery level indicator on the tool and nothing to suggest in the manual of what may happen when battery is flattening.
I am taking this up with Karcher as I only used it three times so far and it it was not a cheap gadget. Hope this helps

it ma be the battery as gone dead

needs new battery get one here http://www.buyspares.co.uk/karcher/window-cleaner/window-cleaner-battery/product.pl?pid=1227185&shop=karcher&path=68315

If the suggestion that renevacdoc did not work, it is most likely that your valve assembly(full bag control) has gone bad and needs to be replaced. You will have to take your vac to the Aerus/Electrolux dealer/service store for repair.
Joe