The answer to 'replacement blowing cold air' is that the most common causes are a malfunctioning blower motor, a clogged air filter, or a refrigerant leak. Symptoms may include the HVAC system blowing cold air even when it's not supposed to, poor airflow, or the system not turning on at all. Solutions can range from replacing the air filter to repairing or replacing the blower motor, depending on the root cause.
For minor issues like a dirty air filter, homeowners may be able to resolve the problem themselves. However, for more complex problems involving the blower motor or refrigerant system, it's best to call in a professional HVAC technician. Attempting to service these components without the proper training and equipment can be dangerous and may lead to further damage to the system.