I've got a 96 s320 that the heater dosen't work in. Took it to dealer and they said there is no cmmunication between the CAN and diagnostic computer. Haven't fond out what's wrong, and could that be the problem why there isn't any heat? I'm new to this site so any help would be appreciated, Just checked the duo heat control valves, have power to center wire but no power to the other two that I assume open and close the valves to allow or disallow water to flow through them. Thanks again for any help.