The unit may be the wrong size for the space it is trying to cool. If the unit is too small, it will not be able to cool the space adequately.
The air filters may be clogged, reducing the flow of air through the unit. This can cause the unit to work less efficiently and prevent it from cooling the space properly.
The unit may not be properly charged with refrigerant. If the refrigerant level is too low, the unit will not be able to produce cold air.
The air ducts may have leaks, which can reduce the flow of cool air throughout the home.
The thermostat may not be set correctly. Make sure the thermostat is set to the desired temperature and that it is set to "cool" mode.
If you are experiencing problems with your air conditioning unit, it is best to contact a professional for assistance. They will be able to diagnose the problem and recommend a solution.