No heat now that its cold outside

Grey_Matter

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everything i searched pointed to the blend door actuator...it still doing the exact same thing.

ok so i warm my truck up, its blowing warm air, within 30 seconds of driving it will be blowing cold air.
both thermostats have been replaced, blend door actuator has been replaced, heater core is not clogged.

after driving for about 10 minutes at operating temp i can open my gas bottle and put my finger in it, and the cooland isluke warm at best.

what do i need to do to get heat in my truck?

2008 F250 6.4L

EDIT:
on another note, i cycled through cold and hot with the key on and cannot hear the blend door opening or closing, i can hear the other two (recirculate and Defrost/Floor/Vent) working just not the one for the temperature. is it possible i am not getting power to it? is there a fuse or is the fuse for the entire control panel?
 
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Grey_Matter

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Update:
Just drove to work, about a 30 minutes drive.
Popped the hood and opened the gas bottle, coolant is cold. Temp Guage on the dash is showing that the truck is up to operating temperature.
Any ideas???
 

webb06

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Update:
Just drove to work, about a 30 minutes drive.
Popped the hood and opened the gas bottle, coolant is cold. Temp Guage on the dash is showing that the truck is up to operating temperature.
Any ideas???



Do you have anyway to see how warm it's actually getting? Via tuner or a scanner of some sort? This will help rule out either the engine or the blend doors.


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Grey_Matter

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I don't have a scanner, but I do know the coolant in the bottle isn't getting hot

The water pump is new and has less than 100 miles on it
 

webb06

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I would check the thermostats. I know they've been replaced but it's worth a look.


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Grey_Matter

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I would check the thermostats. I know they've been replaced but it's worth a look.


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I'm so sick of draining and refilling this system, but I think you are right.

I drained it last night and verified that the heater core is not clogged, after about 2 hours of driving every single hose was cold except for the upper radiator hose, to include the degas bottle

When I did drain it last night I got 4.5 gallons, on refill under vacuum I put 6.5 gallons in, so I had at least a 2 gallon air bubble
 
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webb06

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Then you need to get something to monitor how hot the engine is getting.


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Grey_Matter

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i think i may have found the culprit, the lower hose has a very small leak, im thinking when i put the vacuum on the system its sucking air keeping me from getting the air out of the system, i'll find out when the hose gets here
 

Grey_Matter

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All my parts,are here, I'll let you know if it works....aka new lower hoses and radiator drain plug
 

Tree Trimmer

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where did you get your thermostats from?

i know on my old 7.3 there was long stem and short stem thermostats. if you put the wrong one in bad chit happened.

and you would get sold the wrong one because auto parts stores didn't know any better.

kinda sounds like whats happening here. maybe.

or your new thermostats are stuck open. or not fully closing.

or your water pump is malfunctioning. iirc, if your upper rad hose is hot, then your supposed to have heat to the heater core.

get your truck up to operating temp, and take off one of the heater hoses with the truck running. ya, it should be hot though you stated they were cold/luke warm at best but you should have a fair amount of volume pumping out that hose. make sure you verify it by taking off one hose then the other. verify volume to the cooler, and volume thru the cooler. you just checked to see if it was plugged.

and when the trucks cooled down, you should be able to take the coolant cap off the degas bottle and blow in those heater hoses and blow coolant out the degas bottle. i think. i don't know that one for sure on a 6.4.

put a winter front on your truck or card board up front and physically block a good majority of the air thru the front. try to make the entire truck run hot. if you have heat then, your thermostats are bad, even though you checked them to be good as you need to heat up the entire system to operating temp to get heat to the heater core.

just thinking of a few other ways to check whats already been checked since you don't have a scanner.
 

Jomax

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Are you able to temp check the line going in and out of the heater core with a laser temp gun? Maybe the line is plugged not allowing coolant to enter the heater core?


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Grey_Matter

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I pressurized the system and pretty positive I found the problem, there is a hole in the radiator that only leaks under pressure, so when I'm trying to use vacuum to get the air out of the system it's just sucking air in
 

Grey_Matter

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@Tree trimmer, I'm only using Motorcraft parts from the dealer, I appreciate the help you guys are providing
 

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