After a late-night Home Depot run, I have determined that I do--in fact--have heat coming into the car. Only bad news is that it only comes only out of the passenger side vent, and none of the other vents.

All the vents blow air like they should, so I assume they all work, but I am totally lost as to how heat only comes out of one side and nowhere else in the vehicle. Vacuum issue?

I noticed that the heater core has two lines coming out of it, and based on the goo and sediment that I blasted out of the thing yesterday, I am wondering if part of the heater core is still blocked, while part of it is clear. Would this lead up to the situation I've described?

RSCarey