tomm

Fan was off and I was in "recirc" mode.
It was cold and I had the bright idea to switch the temperature control **** from hot to cold. My thinking was this would stop heat to the heater core and allow the truck to warm up faster.

I heard something like plastic snap and fall down where the passengers left foot would be. Sounded like about an 1/8 inch piece rattling around, not a big door.

As it stands I'm in hot-recirc mode.
The fan changes speed just fine and blows hot air normally out the dash vents.

My thought is, if I turn the temp control **** from hot to cold now, nothing will happen or I may get stuck with no heat all winter. I didn't want to do anything till I posted here so I can't tell you if "recirc or fresh" works or not.

I've read the "blend" door is down that way and you have to reach up and yank it out. Would the temperature control **** have activated the blend door or is there something else down there I need to look at?

Thanks

CatDiesel_762

Sounds like a blend door problem. Take your fan out, which should be in the area of the sound on the passenger side and see if you can see a loose door. You may even be able to pull it out. As for worrying about hot or cold your heat or cooling effect (airflow to top vents) will be lower, but not incapacitated. If you need more info about this search this forum for blend door failure.

Shawn

tomm

What's the difference in location between "recirc" and "blend" door?
Is there also an HVAC door?
I see pics of one behind the glovebox that requires dash removal and one down by the passengers feet that does not.

thanks

mastercaster

the one in the lower center of the dash is the blend door. it blends the warm with cool air. the one behind the glovebox is your recirc door which obviously switches between fresh and recirculated air. i assume your truck is out of warranty. if so, you'll likely want to do the job yourself. it is EXPENSIVE for the dealer to do it. most are charging in the $800 range, and that's to replce a $40 or so part!! i removed my dash myself on my 6.7 mega to remove the airflow diverters that move air to the rear vents of the mega. with those out, i get tons more air flow up front. anyway, i had to get into the same spot to do the job. all told to remove the dash (just pull it back not completely out), cut the diverters out and put everything back together took about 6 hours. well worth the $800 or so to pay the dealer to do it. they wouldn't do that mod under warranty becasue it was functioning as designed (lol..crappy).

mastercaster

oh yeah, and these rigs don't have a heater core valve. there is always coolant flowing through the heater core! tha't why when in fresh and cool temp selected, the air is really quite warmer than the outside air. i did a mod for that also which not onlykeeps the fresh air the same temp as outside air, but keeps the a/c MUCH colder in the heat of summer. basically i installed brass ball valves to cut the coolant flow off from the heater core. look through my posts if interested.

tomm

LOL, no heater core valve!
So my turning it from hot to cold was all for nothing, unbelievable!
Thanks for the advice, I'll be bypassing the core as well, I did that once on an old Mustang when the core sprung a leak all over my shoes. In California I didn't need the heat, unfortunately in North Carolina I do.

Good Holidays to you!

mastercaster

it is pathetic. my '05 superduty had a vacuum valve from the factory. only cut the coolant off when in recirc or max. here in south texas, i can just shut the coolant off from spring through the end of summer, then open it up and have heat all winter.

Jeff in TD

This thread was really helpful...

https://www.dieseltruckresource.com/...d.php?t=210483

rolling18

Jeff in TD.. how much $$$ to have YOU do it??? hehe

ok well, i need to find the source of my nasty odor in the vent system anyway..
i guess ill try and tackle r e m o v a l.. uhhh