Well, having your RD mounted really close atop your dash does allow it to get really hot when you park your car. Not only does your RD have to absorb direct sunlight, but it also has to absorb heat which is radiated from the dash directly underneath it. This is one reason why a lot of people prefer to mount thieir RD's up high and just a bit below the tint strip at the top of the windshield. Another reason, of course, is that a RD which is hardwired and mounted up high is much less noticeable to a thief.

