Hey. Greetings from Estonia. I have a 1999 conversion van and The heater drives me nuts. Only lukewarm Air is coming from The vents. Thermostat looks good, atleast according to the gauge. Pipes to heater core are getting hot and The valve, that controls The amount of hot water going to heater core,does work. Any ideas what is causing My problem with The heat. Also i have checked The fresh Air door arm behind passenger headlamp and it looks like IT is in closed position. Is there any chance that inside the air duct there is some sort of Air door what bypasses The heater core. Also it looks that above the heater core there is one control arm for something but for what? It is kind of tricky to find any diagrams on the internet for Van airduct and its working principles. Sorry for My Bad english

 

Blend door, (the one that controls outlet temp) is controlled by a cable on your van. It may be out of adjustment, or, it may be as simple as an air pocket trapped in the heater core. I know the trucks are notoriously difficult to get all the air out, don't know if that applies to the vans as well.

 

Ok but where is it exactly located? Or is it The same thing what is located on top of heater core and The arm goes threw The firewall. And under The dash, behind The glovebox, you can see a controller?

 

No clue on the Vans. Getting a real factory service manual would likely be a lot of help.

 

subscribing to this as well as I'm currently facing the same issue...

 

I have now gone threw My vacuum lines. All seems to work. And all Air doors are operating, exept door that controlls Air flow to face Area. Reason behind that is one Cracked and broken plastic peace what connects The door and metal arm. Offcourse it is out of production. But conclusion i made is that heater core is glogged and thats why i cant get enough hot air.

 

I gave up and took it to a shop last night. they found a torn vacuum line in the engine bay. Once they got that mended, i now have air going to the face area.

I had a similar problem with the heater not getting warm enough, they did a quick flush of the heater core core and that fixed the problem.