Why is your shop vac blowing out and not sucking in when you turn it on?

could be clogged

Actually, make sure that your paper filter and the sponge filter are placed properly and that the ring that holds it (usually is a ring) is pushed all the way up so that the air has to pass through it. Also, make sure that the ball/plug is on the bottom position (this ball/plug is there for stopping water from getting into the motor when sucking liquids). Initially, it will blow a bit of dust, but if the filters are in snugly, it will suck air and not blow dust. Good luck. Ubanam.