[DML] Heater problems

[Ben Krasnow <kraz@xxxx>]

It's funny to hear about heating problems in the middle of the summer,
but it was cold last night, and I wish that my heater was still working!
I turn the heat control all the way to the hot side, and the vent
control to either the mid-level vents or the footwells, and I get zero
hot air. It worked just fine the last time I used it (last winter). At
first I suspected the coolant control valve was sticking in the shut
position, but it is operating as it should, closing on max A/C, and open
the rest of the time. If I feel the heater hose on either side of the
control valve, I can tell there is hot coolant available after the
engine warms up. The top aluminum pipe that carries hot coolant to the
heater core is also hot near the engine. But, by the the time the pipe
gets to the front of the car it is stone cold (no hot water at the
heater core). Does this mean that no coolant is flowing through the
pipe? Has anyone ever heard of these being blocked before? I recently
changed the water pump on this car, could that have anything to do with
it? Thanks again for the help!