A few of the primary reasons that can cause your AC not to cool enough are:
Faulty compressor
Lack of coolant
Clogged up dirt
Defective thermostat
Dirt present in the coils
Even though these are the primary reasons behind an air conditioner not cooling your room, there can be more as well. So, it is always advisable to call your technician from a reliable company to insure your expensive equipment is working correctly.