What are the possible reasons I am not getting cold air from my air conditioner?
If all is well with your outside unit, I would double-check your AC coil in the main unit indoors. It could be frozen over and thus not cooling the air. This same exact thing happened to us about 3 weeks ago. We moved into a "new" house (new to us anyways, haha) and not many things were being taken care of well... in simple terms, a freeze-over like this can happen because the coil drain is clogged with dust particles and/or sludge. This means there's no where for the condensate to go and leads to a frozen coil. Hopes this experience can help someone avoid a big maintenance bill in the future!
To fix the issue, use a hair dryer or heat gun to melt the ice away. DO NOT CHIP AWAY at the ice since the coils are very delicate and you could puncture one easily.