91 Nissan Pathfinder Fan Blower Problem

My Pathfinder Blower Fan Works Only On Setting 4. The Resistor Shows Continuity Across All Four Terminals. The Blower Switch Continuity Checks Out Per The Manual. All Wires Between The Switch And The Resistor Show No Breaks. I Have Done Every Check Per The Manual, And Can Not Find The Problem. Continuity To Ground At The Resistor Also Checks Out Ok. Any Suggestions?

As it turns out, it was the resistor. The resistor had an interrupting break in the circuit board. As soon as it was put under load, it opened. Sitting on the workbench, it tested OK. So, be ware, the tests in the book may not always be adequate. Also, this is a stupid design. The resistor in the airstream is a good idea, but, the slower speeds require more resistance, more heat, and that is when the air stream is least! Further, in the winter, the airstream is heated! No wonder the resistors fail!!!