Okay to start off bought truck back in August. bought it with 153k and currently has 192k miles. AC worked great would definitely freeze you out of the truck. It has the digital temp control unit with auto setting. So now here is whats going on.

Couple weeks ago started to get cold out and I went to use the heat so i had auto temp set on 80 and it just always seemed cold for 80. So last week i needed the defrost so i choose that option and after 20 mins at idle and temp set to 90 on defrost well i still had to get out and scrap the window clean as it was blowing cool. so I thought maybe a bad heater core but I have to moisture on passenger floor board and coolant level is good. So I checked both hoses coming out of the firewall and both are warm to the touch. My temp guage is always ran a lil under half way but my scan tools claim its running right around 190 give or take a couple. So need less to say I happened to put the heat selector to the floor last week and wow it cooked me out of the truck. So obviously I have something wrong as the ac option works in all vents just fine but I only was getting heat to the floor. Well then the cold front swooped in Friday night and we got some snow and Saturday morning I went to use the truck and it was in the high 20's and low 30's all day and I barely had heat at all coming from the floor. It was warm but well I was prolly breathing hotter than that. So now I'm stuck with lil heat and well its gonna get colder this winter.

So what I do know is most certain is I drove the truck at highway speeds for about 200 miles today and when I got home I went to check the level of coolant and wanted to make sure I had good pressure so I started to take the cap off the degasser bottle which yes I know I shouldn't do this but as the jug showed full on the cold mark and I was able to touch the radiator with bare hands I figured I should be good but was prepared for the worse. and well after being able to take the cap off I guess I can only be prepared for even worse. So go ahead and lay it on me I need ideas as I'm scratching my head.

Oh yea I even thought back in the day we use to take cardboard and put infront of radiatior to help keep in some heat so I tried that tonight and took truck for a spin and went about 20-25 miles and needless to say the heat got a lil warmer but not much and temp guage stayed the same as well.

 

The coolant hoses should be HOT enough to burn your skin (190+ inlet), not just warm. Double check that first.

 

Ok so today I ended up having the truck start to rise on the temp guage after 50 miles of interstate driving so I got rid of the card board and temp went back to what it was before roughly normal. I also emptied the antifreeze out of it and filled it back up. i tried burping the system by massaging the hoses as well put truck up on ramps to get the front end raised. Also as stated before the cap on the fill jug seemed to have no back pressure and I know have went and installed a new cap thinking that may of been the problem. well after putting an additional 150 miles on the truck today and right after shutting truck off I was able to unscrew that cap with no pressure in the system again. Also the hoses are all really hot now. and not sure if there is still air in system but the upper hose isn't as tight as a regular cooling system would be with just a radiator cap. So not sure if I am going in the right direction but the water pump is what circulates the antifreeze. So making it circulate would build pressure..... So would that mean water pump is failing but just hasn't given out yet?

 

if the water pump don't work, the gauge would be hot - RED.. If you measured the coolant to be 190 degrees and that is what the dash gauge reads, then I would assume the antifreeze and pump are good, thermostat works, and level is OK.
If you main problem is the HEAT going to the cab, then you should concentrate on the heater core ... If you have an air pocket in there, then you can loose heat, but that normally also shows up on the temp gauge and eventually the tank level.
There is a blend door that mixes hot and cold to get the temp you select... If you get good Air Cond, then you would think the door is working. It is possible that it is broke and stuck in the AC position, and not heat.... but normally the door will flop around and have neither heat or AC good.
---------- in the end, you need to look closer at the heater core. You need to confirm that you have plenty of flow thru the core and the temp input is 190 degrees... maybe take the hoses off and connect a garden hose and flush thru the heater to see what kind of flow you can handle.... then verify that hoses are flowing HOT fluid.

 

That's an incorrect assumption. I've seen a number of eroded water pump impellers on Fords where the in-dash gauge never budged off the center of the scale. Stupid idiot gauge, IMHO.

No, it isn't the pump that causes pressure in the system, temperature does that. The pump is there to CIRCULATE (ie, move) the coolant through the system.