Blend door question

[Hef]

I have an 08 Super Duty with dual climate control. Heat is intermittent so I assume it is a blend door issue. I can put the heat on 90F and blows cold air but usually if I set it to 74F it blows warm more frequently.
1. Is their more than 2 blend doors with the dual climate?
2. Does the dash truly need to come out?
3. Will this same method happen in the summer, where it will blow hot and cold intermittently?
4. Anything else to check before I assume it is the blend actuator?

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[beau t]

Hef,
I have a 05 f250 (not dual climate control) as of now i have removed the panel that hides the heater core it has i think 6 screws that hold it on only thing i had to remove to gain access was the glove box. i haven't worked on 1 of the newer body trucks so i can't verify they are the same, with the cover off i am able to see the blend door move and the door that moves air from floor/def/vents, the blend door is on the left side- right behind the heater core, the other is to the left of heater core.i can't imagine they changed it to much other than making it a dual system. Anyhow since mines apart if you need pics of anything mentioned I'm probably not getting back around to putting it back together till early next week unless a miracle happens, let me know if needed.

 

[Hef]

Thanks man, really appreciate it. So tonight I let it idle, got all the way up to 160 degrees and no heat, it is 25 degrees here but i let it run a half hour like that. I took the reservoir cap off and squeezed the upper radiator hose trying to get air out (just trying to troubleshoot). I can hit my button in the truck that changes from the floor, defrost, panel, etc and it toggles through them fine. Water pump was replaced a year ago.
Dual climate control i believe has 3 blend doors. I just have some feeling its not the blend door but who knows. Truck has 163k miles on it.

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[beau t]

The only benefit i saw with pulling the cover off thats over the heater core is i was able to see the blend door function so i knew for a fact that part was working. Hoping its something simple for ya! Mine did have a very thin bead of looked like silicon around it to seal it off, at least thats what I'm putting back on it lol. Did it happen all of the sudden, i would think if the heater core had a clog it should of happened over time not all at once. Have you tried flushing out the heater core and see if it has flow or check the incoming and outgoing hose temps- there is also a flow control valve before the heater that could be closed or clogged (at least there is on mine). Hope some of this helps!

 

[hotcobra03]

Unauthorized Access

scroll down to bottom enter resource link

there is to much information to copy

this is ford's manual when you're in

 

[Hef]

Thanks fellas. I don't really drive this hardly at all if the roads are salty but I worry it'll do the same with hot Temps in the summer when I try to use the air. I'll check into these things as the weather permits and check back in.

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[Hef]

I have all new hubs and vacuum lines but auto 4x4 doesn't work......wondering if I have a vacuum leak and it is affecting heat issues any any way? Maybe blend door? Anywho, too damn cold here to troubleshoot now

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[DSG2003Mach1]

I have all new hubs and vacuum lines but auto 4x4 doesn't work......wondering if I have a vacuum leak and it is affecting heat issues any any way? Maybe blend door? Anywho, too damn cold here to troubleshoot now

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typically, at least in older fords, a vacuum leak will cause the ac to default to defrost. When our 05 had broken vacuum lines to the hubs when youd try to put it in 4x4 it would only blow on defrost