The answer to 'replacement not working' is that there can be several common causes, including improper installation, a malfunctioning thermostat, or a problem with the HVAC system itself. Symptoms may include the unit not turning on, poor airflow, or inconsistent temperature. Solutions can range from simple troubleshooting to more complex repairs, depending on the root cause.
If the replacement is not working properly, it's important to first check the basics like ensuring the unit is properly plugged in and the thermostat is set correctly. You can also inspect the air filters and clear any blockages. However, for more complex issues like refrigerant leaks or electrical problems, it's best to call in a professional HVAC technician who can properly diagnose and fix the issue.