Navi will not connect

Hello, Heat and cold are causing the navigation to connect or not connect? That is interesting, but the search should start in the left rear wheel well. That is where the navigation controller should be. (inside the trunk) Check the connectors for looseness or signs of corrosion. Other than that, I could only imagine the antenna is failing. To be honest, the electrical systems of the S550 are too advanced for anyone untrained to service. I'm not saying that to discourage you, I'm saying that to prevent damage to other components. I recommend making sure the module is plugged in correctly, then having it serviced professionally if that does not resolve the issue.