I'm restoring a 1970s HP Frequency Counter and went to replace the 110V AC tube axial cooling fan on the unit to discover that it has 3 wires. The original fan is a ROTRON 1 PH CAP 0.25MFD fan.
I'm a little baffled by the wiring in the unit which I've shown below.
Why is there both a red lead and green lead from the capacitor to the fan?
And, I can detect continuity between yellow and red - is that likely because of the winding?
My replacement axial fan has only two leads, so I'm unsure where to connect it.