I've been trying to get my heater to work in my EF.

Today I used a test light to determine that I have power all the way to the blower motor, so I just assumed the blower was toast. So I went to a junkyard and got another. It lasted about 3 minutes, and died again.

Any ideas what would be killing the blower motors?

 

Their is a resistor in the box that the blower motor mounts to. Try to replace it. Its two screws and a plug. I think it is a 4 pin plug.