My E350 Sedan 4Matic 2013 has developed a temperature control issue. The temperature will only increase both drivers and passenger side. The temperature cannot be decreased on either side. A local shop coded it for me and showed (HU!!) code. They cleared the code temperature control worked fine on the way home but the next day the same issue. Only will increase the temperature. All the other controls on the Climate Control panel seem to be working fine. I have not been to the MB dealership yet as wanted to learn something about the issue before going there. Any thoughts will be much appreciated. It has 47,000 miles on it. Thank you JoJoJim