It is possible the temperature blend door actuator has failed.
Do you hear a thumping type noise when adjusting the temperature? If so, it is highly likely the actuator needs replacing.
Very common
second coil pack back from the front on passenger side
no
On the back of the alternator
Passenger side, 2nd back from the front
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of Ford Expedition
no
The transmission dipstick on a 1999 ford expedition is located on the Passengers side near the firewall / Back of the engine. It should be color Red or Yellow.
4. Two in the front, two in the back.
Front wheel drive
9mm on front 7mm on back
rear 6x9 front 5 1/4
6.5" round in front, 6"x9" in back.