The answer to 'preventive maintenance blowing cold air' is that a lack of proper HVAC maintenance is a common cause. This can lead to issues like low refrigerant levels, dirty air filters, or problems with the blower motor or compressor. Symptoms include inconsistent temperatures, poor airflow, and the system blowing cold air even when it's set to heat.
To fix this, start by checking the air filter and replacing it if it's dirty. You can also check the refrigerant levels and top them up if needed. However, for more complex issues like problems with the blower or compressor, it's best to call in a professional HVAC technician to diagnose and repair the system.