My Car Is Overheating, And I Have Coolant In It. What's The Problem?

You could have a stuck thermostat. This is a little valve that is part of the cooling system and when you start you car it is closed. This is to warm the engine to it's recommended operating tempura tire and also provides the heat for the interior of the car. If the thermostat does not open the car will instantly overheat as the coolant is not being circulated through the engine to cool it while it is running. This is the fast fix and usually is the problem and shouldn't cost that much to repair. If the thermostat is functioning properly then the problem grows but I would check this first!

If it is not using any coolant, then it is the thermostat, if it is using coolant then you want to check tailpipe to see if it is blowing steam, this would be a blown head gasket

Van as no hot air .loses power going all the time

Could be the radiator in need of servicing or replacement.  There are other factors but that is where I would look first.

You could have a leak, and it could be a part... I am not too car smart, but the part has a spring that contracts when hot that allows the coolant to flow properly....