How to Fix the Double Dash (--) Error Code on Your MRCOOL Multi-Zone System

If your MRCOOL multi-zone system displays the "--" (double dash) error, it typically indicates a mode conflict between the zones. This happens when one zone is set to heating while another is set to cooling. Here’s how to fix it:

1. Check Each Zone’s Mode:

   • Inspect the thermostat for each zone to see if it’s set to heat or cool.

2. Synchronize All Zones:

   • Set all zones to either heating or cooling mode. Avoid using the auto mode.

3. Restart the System:

   • After syncing the modes, restart your system to clear the error code.

Tips for Preventing Mode Conflicts:

To prevent the error in the future, manually set all zones to the same mode and avoid the auto setting. This ensures smooth operation and better system performance.

If the issue persists, reach out to customer support for further help.