My heater will only blow hot air at the front.

I am guessing that this vehicle has two heater cores. Am I correct with this guess? I am assuming after readingyour answer that both are restricted, with the back one being totally blocked. Is this a correct thought, since the back seat never gets heat, and the front is hot only while driving and gets cold rather quickly when you stop.

Both hoses for the front get really hot if you rev the motor up, if you leave it at idle only one gets hot. At the rear both get hot only if you rev the motor, otherwise both hoses at the rear are cold.

I have never used stop leak since I bought the van with 43000 miles, of course I don't know the history for the first 43000 miles.

Not yet, but should I just pull it and try to shoot water through it in both directions from a water hose nozzle? It will be at least next weekend before I can try anything.

Iuntil you rev the motor?I took the hoses loose from the rear and flushed water from both directions. I saw nothing but clean antifreeze come from the heater core, then I took the lines loose up front before the wyes and flushed from there, still nothing but clean antifreeze. I then put everything back together, started the van, got no heat after warming the engine until I reved the motor. The lines at the back of the van never got hot until the motor was reved up for a while, then they got hot and I could feel heat, but after returning to idle everything got cold again. Do these vans have a problem with the water pump possibly not pushing the water through the heater cores

Both hoses are cold until you rev the motor then both hoses get too hot to hold. But if you let the motor idle back down both hoses get cold again with less than a minute.

When I took the hoses loose at the back I flushed water through them to the front and reurning to the back. The water seemed to flow fine. Then I took them loose at the quick connect fitttings under the hood and flushed from there, with the water flowing fine again.

Both the front and rear heaters are the same, but the rear one never gets warm. The front heater gets warm while driving but gets cold again upon slowing down and stopping.