Do not modify your vehicle in a manner that may affect its handling, stability, or reliability, or install non-genuine Honda parts or accessories that may have a similar effect.
Even minor modifications to vehicle systems can affect overall vehicle performance.
Always make sure all equipment is properly installed and maintained, and do not make any modification to your vehicle or its systems that might cause your vehicle to no longer meet federal, state, province, territory, and local regulations.
Do not modify or attempt to repair any of the electrical components.
Honda Civic Owners Manual. Synchronized Mode
You can set the temperature synchronously for the driver’s side and the
passenger’s
side in synchronized mode.
1. Press the SYNC button.
The system switches to synchronized mode.
2. Adjust the temperature using the driver’s side temperature control dial.
Press the SYNC button ...