This would be your AC Blend Door causing this problem. It is a door that seems to be notorious for breaking in ford/Lincoln... Ours is doing the same thing and I haven't replaced it yet. You can google "Lincoln Navigator AC Blend Door Replacement" and there is a guy out there that has pictures on how to remove your dash in a ford forum. The dealer will charge anywhere from $1000~$1900 to fix this. You can get away without taking the dash apart if you go to this website (www.heatertreater.net) and do it his way using his part (he has videos). I would only perform this if you are scarred to turn to a wrench and have some good organizational skills...
______________________________________________________Blend Door Problem
Your problem sounds like the common blend door problem on the Ford Expeditions, and Ford Explorer. The door is on a vertical axis and when it breaks, it can swing back and forth randomly giving heat or AC or nothing. The difference on acceleration is the force placed on the door swinging it one direction.
You can check the operation by fully opening the glove box, removing the actuator motor on top of the plenum box and examining the blend door axle (the actuator is under the unit on top of the hump behind the flexible black plastic cover. It is on top of the unit, behind the glove box in the 2002 F-350 though). Pictures of the common fail signature are available on the Related Links below. There are several "free" fixes that mostly are worth what you pay for them. The solution on the web site is solid and proven over hundreds of vehicles and will resolve the problem once and for all.
On a 1999 Lincoln Navigator : firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of vehicle
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of Lincoln Navigator
On a 1999 Lincoln Navigator : The fuel pump inertia switch ( shut off switch ) is located in the front passenger footwell , behind the kick panel ( according to the Owner Guide )
On a 1999 lincoln Navigator : If you are asking about the Control - Trac 4x4 system control dial : ( A4WD ) is Automatic 4 wheel drive , if the back wheels " slip " then some of the power is transferred to the front wheels
According to the 1999 Lincoln Navigator Owner Guide ( 5W-30 )
You can fix a broken linkage in a 1999 Navigator truck by adjusting its Gear Shift.
tell me how to replace a starter in a Lincoln navigator"?
On a 1999 Lincoln Navigator : If it is equipped with the six disc C/D changer , it is in the center console
You can fix a broken linkage in a 1999 Navigator truck by simply adjusting its Gear Shift.
1999 Mercury front and humming noises can because by several things. Tire noises are the most common cause. A tire that is not wearing properly can cause a humming noise.
According to the 1999 Lincoln Navigator Owner Guide : The fuel pump shut off switch ( inertia switch ) is located in the front passenger footwell , behind the kick panel
According to the 1999 Lincoln Navigator Owner Guide : ( 113.6 liters / 30.0 U.S. gallons )