Central locking failure in hot weather

Does anybody have any idea what could be the cause of this problem?

I unlocked the car for an our or so yesterday but when I locked it again the locking buttons on all doors went down, then up , then down then stopped with it unlocked. Attempting to press the button manually had the same result so in the end I had no option but to remove the fuse and lock each door manually.

The only thing I noted was that it was extremely hot over that period and I seem to remember this happening last year or the year before in hot conditions. I don't know what I did about it then but suspect I just left it (although I seem to remember a spot of fuse removal). Any ideas as to the underlying cause because I don't want to risk accidentally leaving it unlocked at some future date.

I rather think that central locking is more trouble than it is worth!

Sticky latch on one of the doors causes similar probs, also a door not shut right does the same.

I wouldn't worry - it'll be cold and wet again soon so it may start behaving again.

Take the door car off on one of the front doors maybe both the lock motor is conected by an grub screw clamp and depending on where it is affects how the doors work I find that I get the symptoms that you describe when it comes loose although when we got ours we didn't know it had central locking until it went off by itself and the wires between the door and the body had broken and the wires happened to touch and triggered it suprised the shit out of me at the time but at one point the adjustment would give the system the lift handle to lock with the pin but know it just locks.