Driving to work last Monday, the heater blew cold air. Tesla diagnosed over the air, and determined I needed a new DC DC converter, and a new heater. Seems that the DC DC blew a fuse, which fried the heater. I thought fuses were to prevent the downstream mechanicals from getting fried. And I thought fuses were a replaceable item. But in these early models, not the case. So a blown fuse required $450.00 in labor, a $2,100.00 new DC DC Converter, a $750.00 new heater and 10% tax. Seriously, $3,656.73 for a blown fuse. That is a design flaw, and an awfully expensive one on my out of warranty 2013 Model S60.