You don't say if the resistor you installed is OEM or aftermarket. I had the same with an aftermarket unit that lasted only a few weeks; an OEM unit resolved that problem. Otherwise can be an issue with the blower motor or connections creating too much resistance.So a few months ago, my heat started only blowing on high. I did my research and replaced the blower motor resistor. It fixed the problem, about two months later, it happened again, and I replaced it again. After about a week it’s now gone out again? What else could it be besides the resistor?