I've got strange problem with the auto doors lock system - when I move the selector from park it locks the doors but when I move it back into P it doesn't unlock the doors but ONLY when rear defrost is on!!(I've got 93 PA with automatic climate control).When rear defrost is off everything is ok and system unlocks.

Just keep the defrost "off" if you want the doors to unlock! Why would you try to get out of the car when the defrost is on anyway?
:iceslolan Just kidding!

Buicks can have some strange electrical problems, however I have never heard of this one. I don't see how the two are related unless the BCM is confused. :confused: