I have a trane condensing unit.. It runs but there is no cold air into house
Anyone know what might be wrong?

Is the inside blower working?
Is the outside Fan Running?
Is the outside unit blowing up warm or cool air?

The outside units huge fan is working, there is air coming through the vents but it isn't cold its more like the outside temperature

The compressor may not be kicking in?
When the inside unit is cooling, the outside unit will blow out warm air.
The compressor is under the fan in the outside unit, may just be the capacitor.

Where is the capacitor? Can I change it? Thanks so much

It should be in the compartment where the wiring goes into. Their will also be a contactor(relay) in there.
Identify connections and turn off power to the unit before working on it.
You may see it bulging, burnt, or corroded, check connections.
I have a tester for capacitors.
Capacitors are cheap, not tough to install, may fix it. I am not a parts changer, but would try this if you have no way to test.
Also capacitors can hold a charge, when you remove the wires with insulated needle nose pliers, touch all connections on capacitor with insulated screwdriver or something.
The charge in a capacitor won't hurt you, but it may make your hand jerk across something sharp.
Be Careful, Good Luck.

Truthfully, last year we had a tech in PHX killed in an attic when he brushed against a 7.5 MFD run capacitor with a sweaty ear.

The charge these things pack can be deadly. Follow Stratmando's advice about discharging the run cap before touching the leads.

Here are some video advice on how to swap them out and there is more on you tube.

run capacitor problems - thermal-medics FREE online air conditioning repair and info site from Phoenix AZ (http://www.thermal-medics.com/my-videos/run-capacitor-problems/)

https://www.youtube.com/watch?v=YVcWasNjsbY