We have an amana outside central air conditioner unit and when we turn it on it squeals and the fan on the unit doesn't turn. When my husband turned it manually it started and ran fine but when it shut down and started back up the fan did the same thing. We are trying to figure out what part needs to be replaced... any suggestions?

I suspect the fan motor is shot. You'll have to install a replacement motor. The fan blade can usually be removed and reinstalled on a new motor.

Look on the motor for the model and get an exact replacement, if possible. If not, talk to a guy at a motor shop and see if he can get you one of the same horsepower and velocity and with the same frame so that it will fit. Be sure and replace the starting capacitor at the same time.

The motor turns on and works with help and we are wondering if it is the capicitor. Is there a way to know if it is the motor or capicitor?

if you have a volt meter that can check microfareds... yes you can check it. Also if the capacitor looks like the top is bubbled or broke than yes its bad.
you can get a capacitor at grainer and try it first. It's a whole lot cheaper than a motor. If the motors blades sin freely there is a good chance the capacitor is just to weak to make the motor run.

It definitely won't hurt to replace the capacitor, first. A starting capacitor costs approximately 3% of the cost of a motor (give or take).

You can try to check a capacitor with an ohmmeter -- but only approximately. You'll only be able to see its resistance drop. This is a very rough estimate of capacitance and with a digital ohmmeter, it's almost impossible to get a decent reading. A voltmeter is not a tool to test a capacitor. Of course, most meters are multimeters or volt-ohm meters.

To check the capacitance, you need a meter that reads capacitance. Those are available, but quite rare. I believe you'd be better off simply buying replacing a starting capacitor and seeing if that fixes the situation.

The fact that you said the motor squeals when it is turned on implied to me that the motor bearing is bad. That will require a motor replacement. If that's not so, (if it only needs a push to start), then replace the capacitor.

Disconnect the power and see how freely the fan blade turns. It should turn freely, and when released, it should be able to coast through at least one or two revolutions.

There is only 20 companies that make volt/multimeters that check microfareds or capacitence. They are not that hard to find. Also they make a tester for just capacitors.
If in doubt just take the old capacitor in to be tested.

The squealing is more than likely the compressor. Since your motor is not running the compressor is over heating quickly and the higher amps and head pressure are making it squeal.