Any debris left in the hose can become a projectile when the vacuum is use as a blower. Always make sure the hose is clear before attaching it to the exhaust port. You can use the hose attachments to increase the force of the blower, but do this with caution. Restricting the blower opening creates a powerful blast of air that can knock small objects off shelves.
Many Shop-Vac-brand vacuums can easily be converted into blowers. The powerful vacuum motor, which easily sucks up twigs and wet objects, can just as effectively blow them away with a simple adjustment of the hose. This is a handy feature if you need to do some minor cleanup in your backyard and a leaf blower is not available. You don't need anything other than the vacuum cleaner and hose to make the conversion.
Open the Shop-Vac using the latches on the side. Pull the latches back, then lift the top off of the machine.
Remove the bag and filter. If there is any vacuumed material in the main canister, empty it out. Close the lid and snap the latches back in place.
Remove the suction hose from the front suction port. Confirm that the hose is clear of all debris. Locate the exhaust port, typically at the top rear of the motor unit. Fit the hose into the exhaust port just as you would fit it into the suction port. Give it a little twist to secure it.
Take the shop vac outside, plug it in, and turn it on. You are ready to blow.