Hi there

I have a frgidaire furnace and need to add a duct fan and power to my blower motor. I need to know if anyone can tell me if I jump the blue wire or the black for the power feed?

You need to tap the one that is hot. It may be a different one depending if you are using heat or cooling. If you want the duct blower to work with both, you may need to wire in a SPDT switch and switch it when you switch from heating and cooling. Easiest way to identify a hot wire is with a voltage detector.

To do simple checks like this you do need some tools. A test light, a meter, or a voltage detector might be the best place to start with. I came across the niftiest gadget for trouble shooting, a voltage detector. They work through the insulation of wires. There are several brands. I have a GB Instruments GVD-505A, less than $15 at Home Depot. Touch it to a hot wire, and the end glows red. Find the doodad that lights it on one side, and not the other, and you have the culprit. You do not have to open up housings and expose electrical contacts. You are looking at where your hand is, not where the meter is. Most people are capable of doing repairs and will get it going and not get hurt if they use a little sense. The voltage detector makes it even easier.

There should be a tap that says EAC an the control board. That will have 110v when the blower is on.