Really weird issues. FSU?

[acpstunts]

So the other day I was heading home from work, when my AC/ Fan just stopped working completely. Ok probably FSU going bad, get in my car next day everything works ok. This has now been intermittent for a week or so. But on top of this my alarm started going off randomly the other evening, to the point where I had to pull the fuses so I dont piss of my neighbors. Then last night I notice the lights flashing as if my alarm was triggered but with 0 noise emitting.

Could this all be the result of a faulty FSU? Or is this somehting more going on.

Btw I also disconnected the Hood Switch, and double clicked the key to disable the interior motion sensors, and still the issue has been occuring.

I should also mention I replaced the battery about 1 year ago, with one of the best options out there. (drawing a blank on what i went with at the moment)

[wfwright2]

These strange happenings are sometimes the indication of the battery and/or voltage regulator/alternator nearing or at end of life. Low system voltage can cause premature FSU failure.
These cars, most BMW actually, will start and run OK with a failing electrical system, but other accessories will start showing issues. Have it checked before the GM, general module, decides it has played along long enough.

Initial problem does sound like a failing FSU, but it only influences the AC fan normally.

Sent from my SM-T337V using Tapatalk

[Gregory891]

1) If you have an E53 (I'd recommend you add the year, model, etc.) to your signature - very helpful so we know for sure some specifics.

2) IF your E53 has the digital / automatic climate control display and you have NO idea if the FSR / FSU was ever replaced, replace it. Your symptoms would indicate that it is time. You do NOT want it to fail when it's cold in December (my experience). The part has been updated - the current design has a plastic base with 29 metal prongs as a heat sink. Original all metal with about 11 prongs. The OEM to BMW is Valeo (I have this in my records). You'll find funny parts offered - I'd endorse a genuine BMW one or Valeo. Hella is simply rebranded Valeo.

3) Your other issue indeed sounds like low voltage, you need to test alternator output (well above 13 V even at idle).