How do I fix the horn on my 1964 Ford Thunderbird

Check horn fuse first. If fuse good then check horn relay. Another way is to take horn off and take the horn wires and test it straight from the battery. If horn beeps then you know its the relay. Simple fix. Lastly also make sure horn has a good ground. Bad ground means weak to no horn. Good luck

Check for 12 vots of power at the horn itself when pressing the horn button. If there is a reading then replace the horn unit. If there is no reading at the unit I would suspect no contact in the horn button/control itself.