My karcher window vac does not seem to charge?

Dyson will replace the unit for free. Call customer service # on the vac with the serial number

Check the hoses for clogs due carpet fibers.

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

Take it apart and see what is stopping it (the motor) from turning .

Check the battery with a meter to see if it's fully charged.

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

basically, the batterie pack is shot and it will cost about £40.00 ish to replace. as you said, a right rip off