similar situation but
My front passenger door lock quits working when it is below about 30 degrees. works same with key or remotes However, it works fine when warm and has been so for three winters. Sound familar?
My rear drve'rs side rear door look quit as well last summer. New acuator at $55-60 from BMA did the trick.
Thanks,
1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment