i have a 2003 Grand Sport and when I start it when its cold the temperature gauge comes up fast but I get no heat blowing at all.
When the temp gets to half, then suddenly it will drop down a bit and I get heat. But until it drops down from half, I get only cold air.

I checked the antifreeze and it is right up.

ANy ideas?
Thanks

 

I am having a similar problem, did you ever figure it out??

 

When was the last time you replaced the thermostat and had a coolant flush?

 

I have a '96 3.3 liter and it does take some time for the heat to arrive, as to the temp gauge, when the needle goes to 1/2 and then drops, it is the thermostat opening

 

Sure sounds like an air lock.
Does you van have rear heat too?