I Have a bmw 420D SE Coupe and i have this problem every winter, when the car is off for a while and i go to turn it on the car dash comes on and makes a small fan noise and nothing else, after about 15-20 mins there is a click sound in the front and the electric seatbelt dispenser goes back into place and the car turns on and runs absolutely fine and if its off for under a couple of hours its fine only when long term standing.

in the summer and when the weather isnt that cold its normal and turns on fine

I have had many specialist look at the car for me but cannot come to a conclusion and i feel like they are guessing as they say its a relay but if the relay was bad wouldnt it give the same problems the rest of the year ?

please if anyone has any idea, let me know

I have ordered a fan motor relay as thats the only relay looking thing i can see near the front where i hear the click sound

battery is new
And starter are good

thank you !