Dave purchased the new fans and thermostats and then set up a day to install them. It was about a week from the time he first inspected the fans to the date he installed them (Maty 6, 2014). In early July, I checked the fans and noticed that one of them was working fine and the other was not. I waited a few more days for a good hot day and checked again several times. Same thing, one working and one not. I called Dave on Tuesday July 8th and sent him an email. He responed immediately via email that he was on vacation, but could look at it when he came back on Saturday July 12th. He arrived Saturday morning as planned and fixed the problem immediately. It problem was simply that the thermostats were not in sync, so one would turn on, cool the attic, and the second was never reaching the temperature required to activate it. The fix was very quick, and of course, there was no charge.