The answer to 'condenser not cooling' is that the most common causes are a dirty condenser coil, low refrigerant charge, or a failed compressor. Symptoms include the condenser fan running but the air not feeling cold, the compressor not turning on, or the condenser coil icing up. Solutions can include cleaning the condenser coil, recharging the refrigerant, or replacing the compressor.
For simple issues like a dirty coil, homeowners can often clean it themselves. However, for more complex problems like a refrigerant leak or compressor failure, it's best to call in a professional HVAC technician. Trying to service the refrigerant system or replace major components yourself can be dangerous and may void your warranty.