Why is the air conditioning not blowing cold air?

There are many reasons why it does not work: its temperature control may have been set too high; it may have lost all its refrigerant because of a leak in the system; its compressor pump may not be working properly; etc...

If you cannot see anything obviously "set wrong" on the controls of the ac unit, the best advice anyone should give you is to call a licensed Heating, Ventilation and Air Conditioning (HVAC) technician to advise you and/or fix it for you. For personal safety reasons only technicians who are licensed to work on HVAC (Heating, Ventilation and Air Conditioning) should do this kind of work because they have the right test equipment and tools and have been trained in how to do this work safely.