I HAVE A 2002 LINCOLN NAVIGATOR AND SOMETIME WHEN I LEAVE IT RUNNING IN PARK...THE EHAT WILL BLOW OUT COLD...(EVEN WHEN CAR IS WARMED UP).....WHEN I START GOING DOWN THE ROAD IT WILL START BLOWING HOT AIR....??? PLEASE HELP-AS I LIVE IN EAST GLACIER PARK, MT AND WE HAVE LOTS OF COLD...THANK YOU-SUNSHINE

Check the heater hose's going into the fire wall for being hot ! You don't need to know coolant circulation diagram . If the heater hose's are hot , problem is inside , temperature control actuator ! How to Fix Car with No Heat Easy

thermostat or low coolant

i would first be sure that the anti-freeze is full

does it throw a code or the engine light on?

Have a pressure test done on your cooling system, you sound like you could have a leak in your system or your system just needs to have the air bled from it. Check your coolant level also, with air in the system and not enough coolant it will blow cold and cause overheating.

It may be that your leveling sensor is going bad. The sensor thinks the bag is low on air, even with the key off.

It may still be low on freon. It can hold several cans.
High side should be around 250psi and low around 35 or 45psi at idle if system is charged.
If you raise engine speed the low can drop below 20psi and switch off the compressor if the system is low on freon.
Could be a restriction in the system, bad relay, or bad a/c compressor-clutch.

Sounds like a vacuum leak.

air trapped in system. Get a flush & fill using an Evac/Fill tool at a shop @ $75. They know if they have this equipment.

That feeling of raising up,only happens when your foot is on the brake and you pull up on the Electronic Parking Brake.

Also what you discribe,could be caused by starting the engine and immediately putting it in gear,before allowing the idle to come down.

I never start any vehicle and drive away. Even in warm weather I let the vehicle warm up about three minutes or more and drive slow for a couple of miles ,until it is in closed loop. That's when the O2 Sensor takes over and controls the fuel system. So forget about saving fuel by leaving on a cold engine. That is nonsense and not fact or theory based.