It's tripping the temperature overload in the motor. The most common cause for this is a clogged hose. Take the hose loose and attach it to the exhaust port under the back cover. You should be able to see if it's clogged and unclog it. I might also suggest taking it to your dealer. I don't think that machine's power nozzle should run if the overload is tripped. It sounds like the wiring may have been modified for some reason, but I can't swear to it. Good Luck!!