The first picture shows the three wires from the fan to inform the control the fan is working.

(The Second Picture)

Shows an example of the wiring Schematic.

Use your Electrical Meter to verify you have the power, 24v DC and 0v to the fan.
Make sure 0v DC is coming out of the Fan, the yellow wire, on 179. If it does your fan is working fine. If it does not have 0v DC signal your Fan is bad.
If you have signal from 179 it will go to the Relay, RF1. The relay will be in the cabinet. If the signal gets to the relay and the relay does not turn on. Make sure it has 24v to on A1 also. If it still doesn't work you need a relay.
The 24v input to the control should come out of the relay when the relay is on, 266 on the example. If it doesn't verify you have 24v at the common, pin 11. If the 24v out to input isn't sending out of the relay your relay is bad.
If the relay is working correctly and you still do not see the X input turning at the control its the wiring to the control.

Spindle Cooling Fan Alarm