Civic Central locking driving me nuts!

Hi folks,

My car is a Civic 1998 EK sedan with a central locking that is erratic in behaviour...I do not have a key remote so locking/unlocking is done manually by key or by pulling the door tab from the inside of the drivers door. Besides the driver side door which always opens/closes manually, sometimes only one other door will lock/unlock or at other times none of the doors will lock/unlock and yet again sometimes all doors will operate correctly and lock/unlock......I'm not really sure of this but it would seem that the condition seems to be weather related (crazy isn't it?) as during cool weather generally all doors open/close whilst during warmer weather the behaviour is erratic.
I pulled off the trim off the drivers side door and checked the control unit circuit board for dry joints (as per another posters suggestion) , resoldered the relay and connector tabs but this did not resolve my problem .....I guess this still means that I could have a bad earth or +12v connection, a weak/bad door actuator that is affecting the others or a faulty control unit. I managed to get hold of a US service manual but the cable connections to the control unit appear different to mine so I could not follow their test procedure. Does anyone have a wiring diagram of the central locking unit or ideas on how to diagnose the problem?

Any suggestions are most welcome.

Many thanks.