No Heat - heater not working?

I have a 2000 ford expedition that has had no heat for the last two years. I tried thermostats
and flushed and flushed the system again and again. Flushed the heater core again and again. No heat. Changed the waterpump too. No heat. Flushed theheater core. No heat. And yes at operating tempature both heater hoses were hot. But no heat. So I said to myself what I have been deading heater core? Yes I changed the heater core. And guess what? Heat like you would not believe!I took the old heater core and sawed open the tanksand it was pluged solid with sludge. Turned out only two runs were open. With fluid being lazy it took the path of least resistance and thats what was keeping my heater hoses hot having me think there was good circulation. So for all you outher guys driving igloos on wheels be ware of the heater core when all elce fails. Warning this is not a small job! Aprox 11hrs. I am a licenced tech and its quite a job. The whole dash has to come off clear to the firewall in order to get heater core acess. Hope I have been some help brian.

Not getting any heat in the rear of my 2000 ford expedition what could be the problem?

I have a 2000 Ford Expedition that the heat does not work. The air works great but when you turn the heater on, it seems as though the air is still on-there is no change in the temp of the air coming through the vents. What could cause this to happen?

I'm not actually sure. It is my husbands trucka nd we just bought it 4 days ago. He thinks it is automatic.

I cantfindaheatercontrolvalve and everyone tells meitsthe blender door that's causing me to have no heat. Butifit was the blender door wouldn't I still have heat at the rear unit? Can you help? Thanks

The front heater is not getting hot. I replaced the control tempture module. Still no hot air.
The rear heater does get hot.

Where is it located? Behind the glove box?

Ok my heater blows but its not getting hot at all and there is a clicking noise in the rear driver side panel.
And when u turn a corner there is a grinding noise in the rear end its acts like it trys to lock up.
And how do u change the plugs in the 5.4 triton

One day my heater works fine, the next day. Not so good. I have the digital gage to set the temperature I can set it to the highest temp and it only feels like "luke warm" air. The thing that confuses me is my heat works fine in the back rows? All the blowers are working, but I do notice my windshield fogging up more than usual? Any help would be appreciated Thanks

? I feel like I always get ripped off when I take it to a shop. Could you estimate what this might cost, or what needs repairing? All they tell me is its my heater core and it will over a $1000. Once again, any help is appreciated.

I have noticed that it is beginning to take longer and longer for the car to heat up. The heat blasts, but it's not hot air until 10 minutes later just about. Possible suggestions?