Just had dealer replace blower motor and blower motor regulator lasted about 3 days same problem again no heat

The S550 is a very complex car especially with electronics. I'm sure you just spent a lot of money getting this repaired at the dealer so you should bring it back in right away. We could guess at a few things but in the end they should cover the repair. Alex

There is definitely a fix if you get the right person to work on the car. We can guess at a few things here but ultimately I wouldn't recommend trying any of these repairs considering you have a warranty. The car needs to be properly diagnosed and your warranty should cover it. Alex