The water level is up, the heater hose is hot on both sides of the heater hose bypass valve, the MtrCrft thermo is pretty new, but it blows cool air out the vents even after a half hour of driving. It was working great last week and then nothing. I guess you can see the blend door moving if you pop the glove box out?..........haven't tried that.

 

Not that I really know the answer on this one, but I was wiring in that new mirror this past week, I had to start the truck several times and had the glove box down (it was flipping cold out) so I had the heat on....so ya you can see it just by popping out the glove box stoppers and lowering it down. Honestly wasn't sure what it was but I noticed it move while I was running some of that wire accordian tubing stuff around it and looked it up later because I didn't know what it was.

 

I found this on Youtube;
They say if the axle has black powder on it it's probably bad

 

And here is one for the heater core (not too bad).

 

And this is if you have an Expedition;

 

Now that is funny.

And sad too since all too many cars are the same story.

Just throwing a guess out there. Are the blend doors vacuum operated? If so, could you have a vacuum line off someplace?

 

I haven't gotten that far yet, I was just looking for some possibilities for now.

 

This is what's in mine

 

The hoses on both sides of the re-routing valve are hot and the one below is cold but is there another hose I should be checking? Also; there are 2 water pipes behind the heater core and the one on the left is very hot but the one on the right is cold, also; the cover on the heater core is cool to the touch. Also; the blend door rod and lever move up and down when you switch the heat from floor to dash.............but still no heat, it just pushes out lukewarm air. The rad tank is filled up the the max fill line and the top rad hose is hot to the touch.

 

Looks like the return from the heater core is cold in your picture. Might mean the heater core is plugged up. Or the valve isn't allowing full flow to the core. Even though the hose is hot right after the valve it still might not be flowing fully.

Turn the heater off and see if the hose out the bottom of the valve gets hot just to know the valve is at least working like it should.

 

Now none of the hoses get hot (under the hood) but the top rad hose is very hot. I was thinking of getting a HVAC/heater bypass valve but none of them show a bottom tube even though there is a hose coming out of the bottom of mine.

 

When you shut the heater off (turn to cold) does the valve warm up along with the hose in and the hose out the bottom? If not and the radiator is warm I would be looking at the valve first. Especially since you said the heater was working good the other day. Normally when cores plug up they slowly get worse and worse, not just an over night thing unless a chunk of something blocks a hose.

 

Nothing warms up now and I don't see how the core could get plugged up in one day either. It is strange how earlier today it was hot on both sides of the valve and the left pipe behind the core (under the dash) was too hot to touch but the right one was cold.
I have a new valve coming from Amazon (with the bottom tube) and it was $35 with free shipping .....Motorcraft.

 

Most likely the valve. It can be hot all the way up to the core if it flows just a tiny bit but he core sucks the heat out of the fluid before it leaves the core causing the cold output hose.

 

No, they are electric.