My central air unit in my basement is running but the square unit outside that houses the fan -the blade will not turn. The unit outside sounds like it is running-but just makes a humming noise and the outside is hot to the touch.

Any ideas??

First off turn off the a/c unit! The outside motor will overheat and burn up. It could be your relay switch is bad. It's located on the outside unit.

Turn the unit off and kill the power. Try to move blade manually. If it turns manually maybe just need to replace capacitor. If not than you need a new fan. Alswyas replace capacitor with a new fan.

My central air conditioner works and blows cold air for a minute or so and then when the fan tries to kick on to cool the motor, a real loud squeal starts and the fan doesn't kick on. What could be the problem?