Most of the time years of paint or caulking the seams around the panels will cause the wood to stick and not allow the panel to expand and contract with the weather.
Repairing a split door panel.
If a crack has gunk in it clean out the space with a strip of sandpaper.
Once the broken panels slide use a hot glue gun to attach wooden blocks to both side edges of each of the panels.
To do this you need to glue wooden blocks on both sides of the panel along the split.
How to fix cracks in door panels without taking the door apart wooden doors will develop cracks over time especially if the panels aren t free to expand and contract.
With a painted door assuming the frame and everything else is ok repairing a split panel is as easy as filling the split or crack with the appropriate wood filler letting it harden and then sanding it down and painting over it to match the rest of the door.
Be sure to place the block on areas that will be covered by the pieces of moulding once they are replaced.
One difficulty in gluing up a door panel is clamping it.
Repairing them without compromising their integrity required patience and an understanding of their mortise and tenon joinery.
Natural or varnished doors.