I bought a 2006 V70 over the summer and it's been great so far, but I noticed early on that the interior fan wouldn't shut off without disconnecting the battery's negative terminal. Even with the key out of the ignition or if I have the speed set to the lowest option the fan seems to be consistently spinning at Mach 10 no matter what. In the summer this was okay as I just opened the windows and never used the fan but living in Canada in the winter it has been a challenge not only heating up the car but more importantly, defogging the windshield if I don't use the fan.

From the research I've done on this forum, it seems that the blower motor resistor is the most likely culprit of this issue. It's worth noting my car was originally a show vehicle for a mobility scooter company and it had a robot arm fitted in the trunk. My CEM shows up as a critical error which I suspect has to do with whatever the mobility scooter company did to get a robotic arm to deploy automatically for their clients. I've driven the car over 7000km since owning it and it has worked flawlessly mechanically and electronically, everything besides the blower motor of course.

Is it worth replacing the blower motor resistor or could my issue be because of the CEM error? I'm not sure how a CEM error would manifest itself as an issue in the car but nothing has happened yet. Ideally, id like to avoid going to the mechanic but my guy is pretty good so I'm sure he could diagnose the issue and fix it but it would obviously cost more than id like it to.