I have no heat at all in the front of my lincolm nanavigation heat in the back

If the front heater does not blow any air suspect a defective fan motor or resistor. You can try turning the blower on and banging the underside of the passenger dash to see if it begins working again. If it does, suspect a bad fan motor. If blowing only cold air, the most common problem is a low coolant level

your vent selector is stuck

Try to back wash the heater core first if it doesnt work then its clogged up try to turn the heater on the front with the heater off for the back keep an eye on the temp guage if it goes up than normal then its clogged....

Fyi u have to run the engine for awhile with the heater fan on

possible blower motor

Usually a sign of low coolant or a blockage in the circulation.

see if theres power to the rear blower motor go under the rear and see if the one pipe is cold and the other is hot or at least warm if there the same then the rear system is plugged

Most air ride systems have a intial start up diagnostic program that will tell you there is a problem with your air ride system. Do you have any diagnostic errors kicking out? If you don't find the air ride on off switch and make sure it wasn't turned off by mistake. There is usually also a seperate fuse for the air ride systems (on my Lincolm VIII is is labeled RSS) which is close to the on off switch (my in on the drivers side rear quarter panel - trunk). That it if blows will totally skip the diagnostics on start up.

When I turn on the heat in my 2004 mazda mpv the front air vents blow heat but the rear air vents are blowing cold. I have adjusted every setting is there something I am overlooking.

If you can get cold air blowing out the front vents, the front heater door is not working properly. If you don't get air blowing out, check the front heater fan and its resistor block.

It sounds silly but there is a separate unit in your console that you can only turn off if you go in from back seats. You probably already did that, but if not try. You can not turn it off from any controls on front panel. If it doesn't work, I would think something is wrong with the switch. Open it up and look at wire connection from switch regulator. It also has a heat regulator on the console facing back seats? Mine does anyways.