Idle drops when heater fan is on

[dinu.negrean]

When I bought this car someone told me you never get bored with it, and that seems to be very true. I'm always "in construction", on problem solved, two more on the rise. Most of the times is challanging, sometimes not so much.

Symptoms
When I'm driving with the heater fan on full speed, redlight comes on and I slow down and take the car out of the gear, the idle drops quickly to 350-400 rpm almost stalling, it does it twice then it's stable. Very annoing when driving around town we have a lot of semaphores, and each time I slow down, or make a turn it almost stalls.

I replaced the battery, it is brand new 62 Ampers. The old one on the car was a 55 apers and behaved the same.

On idle I measure on the batter 13,92 V and exiting the alternator I have 14,1 V, I imagine I am loosing some tension along the way, but I don't think that little would cause this problem.

If anyone ever experienced similar issues please give me a hint on what else should I check.

Regards,
Dinu

[BlueBMW]

Mine does the same although its when I have the A/C turned on and I come to a stop sometimes it pulses up and down a bit threatening to stall.  My thinking is maybe a slow idle control valve or something.

[dinu.negrean]

I have the feeling it is an electrical issue. But I'm not very good with the electric part so maybe someone here who knows this part better can give us a logical explanation of why this happens.