Migue -
My Central Air Unit broke when we were in the 104-5`s a little while back..
The Condensor unit that sits outside only has 4 parts that can break -
Run Capacitor, or Contactor
Compressor
Exhaust Fan motor..
The Compressor would be the most expensive thing to replace.. You would need an A/C guy to do this one because they have to discharge the Compressor and then charge the new one with the proper amount of gas to get the cooling temp and pressure set correctly..
The Air Handler Unit is usually inside in a Closet, or up in the attic, usually in the hallway so you will see the air filter screen, and you drop down the screen and the air filter drops out to replace..
The Air Handler just moves the air hot or cold from whichever unit is working..
So it`s either going to blow something or not blow anything..
Here is a great YouTube video that may help -
https://www.youtube.com/watch?v=14xhAxPfxIo
It might just be the Run Capacitor and/or Contactor and if that is the case, these parts are available at those Appliance Parts Stores, etc..
If it`s the Fan Motor that sounds terrible, grinding, etc, when you turn it by hand, that motor can also be purchased at an Appliance Parts store...
The only thing you have to do is remove the existing Fan Blade from the old motor and install it correctly spaced like the original one from the top of the shaft, and it should run great with no noise or vibration...
Usually, the Appliance Parts Store will have a Fan Puller tool right there on their counter to help you get that fan off the old motor and then you mark how many inches exactly it was from the old one and install it at that point on the new motor...
Dan F