FSU Replacement Still Not Functioning Correctly

[andermic]

My hvac blower stopped working a few weeks ago. I did a lot of research and agreed that it was probably the FSU (final stage unit or final stage resistor). I ordered a replacement FSU and promptly installed it. The hvac still didn't work. I did more research and someone suggested that the motor might just be stuck. So I took out the FSU and directly wired the blower motor and it kicked on. I then put the FSU back in and it worked. I was super excited until I drove for about 10 minutes and it shut off again. I replaced it with the original BMW FSU and I get the exact same symptoms. So at this point, either both FSUs are defective, or something else is wrong. If I turn off the hvac for a couple of minutes, it'll work for a short bit when I turn it all back on. Could something be overheating?

Summary: Replaced FSU, it works, but only for 10 minutes. It'll work again if I turn it off for a bit.

I want to see if anyone has any suggestions before I return the FSU I purchased or end up bringing it in to a shop.

[andermic]

As a followup, I bypassed the FSU last night and directly connected the power to the blower motor. I drove around for about 30 minutes and it continued to run. Because of this, I believe that my issue is that I have a bad FSU, and the replacement is also bad. I plan on picking up a BMW FSU and seeing if that works.