When the lock clearly releases and the door still will not budge, the fault is mechanical rather than electrical. Consequently the fob and the actuator are working, and something between the handle and the latch is not.
The handle linkage
Inside every door, a rod or cable connects the handle to the latch. Consequently when that linkage breaks or unclips, the handle moves freely and nothing happens. Furthermore, it usually fails on one door only, which is the clearest diagnostic you get. Therefore if three doors work and one does not, suspect the linkage first.
Frozen latches in Ottawa winters
Moisture gets into the latch, then freezes. Consequently the mechanism holds even though the lock has released. However, forcing the handle at this point snaps plastic components, which turns a free fix into a paid one. Therefore warm the area rather than pulling harder.
What actually works
A hair dryer or warm air from the car heater, given a few minutes. Meanwhile de-icer sprayed into the latch helps. Above all, do not pour hot water on it, because refreezing makes it worse.
Child locks and the obvious check
Rear doors have a child lock switch on the door edge, and they get flipped accidentally more often than people expect. Consequently a rear door that opens from outside but not inside is almost always this. Therefore check it before anything else, since it costs nothing.
When it needs opening up
If the linkage has failed, the door card comes off and the rod or cable gets reconnected or replaced. Consequently it is a straightforward repair once access is gained. Moreover we do it without breaking trim clips, which matters because replacements are rarely in stock locally.
Questions we get about this
Only one door is affected. What does that mean?
Almost certainly the handle linkage inside that door.
Can a frozen latch be freed safely?
Yes, with warm air and de-icer. However, do not force the handle.
Should I pour hot water on it?
No. It refreezes and makes things worse.
My rear door opens from outside only.
Check the child lock on the door edge first.
Do you have to remove the door card?
Usually, and we do it without breaking the trim clips.
