HVAC Fan wire not getting 24 Volts.?

Read the service manual for your unit and also read both a basic and an advanced electrical theory and application book before you go any further in this project. If that is too long a time for you call a local HVAC technician to do a service on the unit. I would suspect either a bad fuse or an error on the part of the operator trying to diagnose a problem while lacking the needed education on the equipment.

I might determine the circuit breaker for the compressor (if this can be a split A/C system). Some times these travel as a result of the detail being weakened because of voltage surges (storms, etc.). Also, if you think comfy doing this, assess the vigour on the road feeding the compressor to see if you have voltage. I might simplest do this in case you are experienced with electrical circuits---it can be unsafe. It would be the capacitor for sure.

Are you talking about the thermostat line?

Your fan motor should be 240VAC and If you're checking the big green wire you're checking the ground- which shouldn't have any voltage.

Can you hear the motor humming, or any vibrations when you touch it? That's a capacitor problem.