Sounds like the contacts of the 110V relay are welded shut such that the DC's motor control is activated applying power to the motor. There is a chance it could be the DC's main power relay/contactor but being a 220V circuit 2 contacts would have to stick shut.
If so, fix is to replace the relay. Can you see which relay is stuck closed? Remove the power from both circuits before sticking your nose and fingers in it!!!
If you can get access to the contacts you may be able to "pry them apart" and they may open fairly easily. Before putting it back into service get a very fine file or hone or some carborundum paper and smooth the contact surfaces. This should be considered a temporary fix since the contact surface roughness will likely cause them to stick again.