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· Registered
2016 M235i 6-spd
29,215 Posts
Add a switch inline somewhere.

But, this is the first we've heard of such a thing here. Where is this heater? In your hvac box instead of the heater core...or is this the heater core and it just has some electric control unit that's drawing power?

You have a complete PN for it. The one you gave is too short.

Realoem.com might help too. That appears to just be a heater core and it would be heated from hot coolant, not from an electric heating grid, if that's what you think. Ah...there's a temp sensor on it, I believe. Sadly, I think the cost of getting to it through the dash would be high...though I wonder if that sensor might be accessible. I bet that's it...a temp sensor...

or...another theory. You got a new battery and maybe have a failing alt, loose/corroded cables, or you don't take long enough drives to ever get the battery charged fully. You might take lots of short trips and the battery is just weak. You have the volts but not the amps...and it's running low in 3 days. If you have a charger, charge it overnight.

Run the cluster test for voltage and see what Volts you're getting with car off and on...might be just a coincidence...and your mechanic might be picking up just the natural drain the car has while it sits and does nothing.

Finally, another theory would be you got a new heater core because you didn't have heat...and your old heater core was fine but your fan wasn't working because the fsr was broken...and it will drain a battery...very common issue.

...a few theories for you...does your mechanic seem reasonably intelligent?
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