Of course you can. But be advised that even with the pump off the machine will consume water (or in this case antifreeze) at least my 405 does. So I'd hook it to water (direct from hose not fresh tank) and then re-winterize it when done. Once you get good at it it takes 5-10 min to winterize the machine. Our old Steam Action back in the day we winterized after every job that there would be more than an hour travel time. It was mounted in a trailer without heat and Maine gets bloody cold in Feb.