The answer to 'installation not working' is that there could be several common causes, such as improper installation, electrical issues, or problems with the HVAC unit itself. Symptoms may include the system not powering on, poor airflow, or the unit not heating/cooling properly. Solutions can range from simple troubleshooting to more complex repairs, depending on the root cause.
For minor issues, some basic DIY troubleshooting and repairs may be possible, such as checking electrical connections, replacing air filters, or resetting the system. However, for more complex problems or if you're not comfortable working on HVAC equipment, it's best to call a professional HVAC technician to diagnose and fix the issue.