knocking sound wen heater is on

The knocking sound when you switch to heat is probably the actuator which moves the blend door having a broken cog on the plastic gear. When two or three in a sequence break, the sound will go away and the system will be stuck at hot, cold, or somewhere in between until it is replaced.

The door ajar light can be caused with the plastic collar around the lock striker (screwed into the door pillar) is worn off and you end up with metal on metal. The plastic is not replaceable, except for the rear hatch, a new striker must be purchased. Don't waste your time going to Ford, they usually do not stock them. They will order one for you at a price of about thirty bucks a piece. You can get them on the net for about fifteen.

Check each lock on each door, in turn. With the door open, manually push up on the latch which engages the striker, it should snap all the way up. See if the pulsating of the lock stops. It can be returned to it's open position by pulling on the handle inside the door and pushing the latch down with your finger.