Yep. I noticed mine with heat. In fact since my car is black, for awhile whichever side of the car was facing the sun would not work, but the side shaded from the sun worked fine.
There's a fix for this one... not sure if it would also solve the OP's issue but maybe.
Search Youtube... I can't recall the guys name or channel but I think there are several YouTube videos out there showing you how to put new motors in your door locks.
It boils down to pulling out the...