The answer to 'system upgrade not cooling' is that there could be several common causes, such as low refrigerant levels, a malfunctioning compressor, or issues with the ductwork. Symptoms may include the system running constantly but not cooling effectively, warm air coming from the vents, or uneven cooling throughout the home.
In many cases, these problems require professional diagnosis and repair by a licensed HVAC technician. Attempting DIY fixes can be unsafe and may even worsen the issue. A technician will be able to thoroughly inspect the system, identify the root cause, and recommend the best solution, whether that's a refrigerant recharge, compressor replacement, or ductwork modifications.