RVP and Dometic are the only REAL major suppliers of RV AC units. They have the majority of the market and have for 40 years. The Brisk 11 is a common AC unit. Being on your 3rd? That is extremely unusual and I would suspect that the others were not diagnosed properly or not installed properly. As to your current problem, THAT is a control issue and while Dometic makes the control box and the Tstat, it is NOT part of the Brisk Air itself. Those 2 parts are not replaced when the roof top unit is replaced. This leads me to believe that they replaced the previous units(were good) because they lacked the skills to diagnose the real problem. Explain the blower motor shut off better. Does it shut OFF and then come back ON or does it shut OFF and then a few seconds later the compressor shuts off? Which Tstat do you have? Dometic makes a few different ones. Is the tstat fan on AUTO instead of Hi or Lo(med if you have a med)? Doug