The answer to 'system upgrade blowing cold air' is that there are several common causes, including a refrigerant leak, a problem with the compressor, or an issue with the ductwork. Symptoms can include the system blowing cold air but not cooling the home effectively, or the system cycling on and off frequently.
If you're experiencing this issue, it's best to call in a professional HVAC technician to diagnose and repair the problem. Trying to fix it yourself can be dangerous and may cause further damage to the system. A qualified technician will be able to identify the root cause and make the necessary repairs to get your system working properly again.