On my 99 CC the Webasto light that turns red should go out when the unit is not running. Stays unlit.
The only calls for heat are the thing I mentioned before, the thermostat for any of the two zones, the engine heat loop, the hot water heaters or the bay heat coils in the plumbing bay.
If your Webasto light is staying light all the time even if you have turned off the central heat button, there is a problem with the card in the ECC cabinet.