Off topic, I guess, but why would a door leak make the cabin colder? It's not like cold air's leaking in from outside.
That's physics for you, same principle as a refrigerator or air conditioner, look up adiabatic gas expansion. It basically states that a mass of gas rapidly expanding into a larger volume will cool down. If you've just removed half the gas in the fuselage through the leak, the other half will occupy the whole space and the temperature and pressure will drop.