My overhead door light does not come on when the car door is open even though it has a new bulb and the side door lights work when the doors are open. What could be the problem?

Also, even though the radiator has a brand new cap, I can stay inside the car and hear the coolant boiling inside the reserve bottle after the vehicle has stopped driving.

The mechanic checked all the hoses and didn't find a leak. What could be the problem?