I have a 2008 convertible. About 50% of the time, when I start the engine, the HVAC doesn't come on. It appears there is power to it cause i get the backlighting, but no display and no functions work. It remembers last setting so if I had the A/C running, the A/C comes on, but I can't change any settings. After several minutes, sometimes it wakes up and I have full control. Other times, it stays inop for the entire drive cycle. Any else experiencing this?