My variable speed type worked flawlessly for the short time I used it. That van however has been out of commission (for other reasons) so no word on reliability/longevity. I do like the idea of electronic monitoring/triggering of the fans, and think it's going to prove to be a better system. In my experience the capillary type with the relay tend to only go a couple years before failure. Perhaps it was just a fluke, but I don't trust them anymore. Tim

PS: perhaps reading reviews on amazon or where ever these are sold might be a good idea.