07 Pathfinder blower issue

[cdretc]

The blower only works on setting 4, but A/C only turns on on settings 1-3. When you turn to setting 4 A/C turns off. Replaced blower resistor w aftermarket from ebay. No change. Switched the 2 brown relays in the engine bay, same thing. Checked all the blower fuses, all good. Any new ideas?

[VStar650CL]

It's either a bad switch or a problem in the Blue wire someplace between the resistor and the switch. High speed cuts the resistor completely out of the loop and just grounds the blower directly through the switch. The Blue wire to the resistor and associated internal switch contacts are common to all three lower speeds.