A lack of cold air may be caused by any of the following:
The fan is set to "ON" rather than "AUTO" which blows air around the clock, whether or not the cooling system is engaged.
A dirty air filter can hamper airflow and may freeze the evaporator coil.
Dirt or debris surrounding the outdoor unit can prevent the condenser from dispersing the heat collected from inside your home.
A low refrigerant charge or leak prevents the AC from absorbing enough heat to cool the air.
A malfunctioning condenser fan motor will prevent the condenser from dispensing heat.
A faulty compressor prevents the circulation of refrigerant, needed to remove heat from your indoor air.
And more—talk to a professional for a diagnosis of your cooling issues.