My 98 windstar is randomly overheating and no heat

Two different issues. The vents and hot air is caused my a cold air mixture door motor gone bad, it's very common. Replace the blend door motor to fix that issue. Overheating could be caused by many things including non working coolant fan, bad t-stat, bad water pump, low or leaking coolant or excessive buildup in coolant system.

fill the rad to total capacity, also your heater core is most likely "air locked" you nede to loosen the return line from the heater and with heat set to high and engine running, allow fluid to leak from the loose connection until all air bleeds out. since the heater is higher than the water pump it will not force it out on it's own. you could get a mechanic to do this for you but why waste money for a simple fix

The hose from the valve cover to the air cleaner is just a fresh air source for the crankcase.
What you are describing is a radiator low on coolant or has air in the cooling system.

It could be your heating coil. It seems that your fan is running (at least to the outside vents). Since your temp. is fine there is probable not a problem with your coolant. As far as it not blowing through the vents in the middle couldn't tell you.

To troubleshoot this types of problem,click the link below :----http://howtobyme.blogspot.in/2012/02/heater-blows-only-from-defrost.html
--------Go through the procedure to confirm the issue.

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Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Heat blows cold on drivers side and hot on passenger side?

http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

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For car running hot and overheating issues, I suggest to you go through this help links. Click this link below and go through the troubleshooting procedure to take care of the problems: ----Car runs hot? http://howtobyme.blogspot.com/2011/11/car-runs-hot-in-traffic.html
-----------All types of car overheating problems and troubleshooting?

http://technoanswers.blogspot.com/2011/11/all-types-of-car-overheating-problems.html
Car freeze overnight and started overheating while driving?http://technoanswers.blogspot.com/2012/01/car-freeze-overnight-and-started.html-----------Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Car overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
--------overheating? http://schematicsdiagram.blogspot.com/2011/12/buick-century-overheating.html
----------Car engine Overheats and transmission starts slipping?http://schematicsdiagram.blogspot.com/2011/12/car-engine-overheats-and-transmission.html
----------This details will help.Thanks.

the most common cause would be a slow leak in the system, and Freon might have been lost, causing warm air to blow Simply recharging an A/C system never fixes anything,so it needs to be checked for leaks

The paths through your climate system are controlled by blend & diversion doors that are controlled by your settings and actuated by vacuum 'motors.' If you live in a hot climate, you may have cracked vacuum hoses which can cause the kind of random air temp and mix you are having.
If you have never had any maintenance done that involves rubber products, it may be time to do it.

possable problems:

1. coolant leak (level too low to fill heater core)
2. headgasket leak forcing the coolant out of the overflow.
3. stuck thermostat.
4. bad water pump. if the impelers are broken, coolant wont flow.
5. HVAC malfunction. system may think you selected cold or is unable to move diverter. maybe a fuse,solenoid or vaccum leak? (hvac controler uses vaccume controled soleniods)
6. airlock. if you have resently changed your coolant, you may need to repeatedly squeeze the heater core hose to help force out the air.

there is a white box under dash that controls the hot and cold air. it has wires running to it. this has to be replaced.

If you have the heater directed to the windshield, the AC will turn on. Move the control away from defrost.