where is the fuse/relay located on a 2010 lincoln town car?

Note the diagram. See the two wire connector at blower motor, check voltage and ground, the top wire is voltage, in the diagram, the bottom wire is ground. You can use test light to check voltage and ground. As you can see the blower motor speed control is on the blower motor ground circuit. I don't know exactly what testing you have done, which circuits?

Put mouse arrow on diagram and click to enlarge.

Don't forget to reconnect all the wiring near the new fan you just installed! Then try blower again,