Hi Folks, been trying to find out some info on the Recirculation function for my AC. Seems for a long time it has not worked.
Any idea where I begin? When I push the button, I hear no sound like would expect a door to open/close and also when driving, I can smell anything outside where I recall when it did work, it was helping to prevent exhaust smells from other vehicles in front of me, etc.

I find lots of blend door issues and have replaced the actuator before on that one, but not sure about the recirculate part of it?

 

With your head under the dash (passenger side). Literally!

There should be a white vacuum line that comes from the vacuum switching plumbing. It should tee and go to two places: One will be the recirculate vacuum motor back behind the glove box area (remove all the stuff and release the tabs so the door hangs down) and the other to a vacuum-controlled valve under the hood on one of the heater hoses (if equipped with that feature). That white vacuum line should have full vacuum when the climate control has recirc switched on.

If it doesn't, could be a leak or a vacuum solenoid or control problem. Just have to start with identifying stuff.

Since you have a Limited, I'd assume you have the EATC in which case you have a remote vacuum solenoid for vacuum switching. It's buried somewhere back in the dash.

 

Pull the fan off the firewall. 3 small screws/bolts. it's pretty much the only way to see if the door is operating. start your rig and turn on the AC. obviously the fan won't come on. but the blend and intake door will position (need vacuum to operate).

In normal vent modes you can look straight through the fan housing and into the interior of the dash.
When in recirc mode (max ac for manual controls) the door shuts and prevents air from intake through the cowl

if the door doesn't operate, you have a vacuum leak. you'll need to chase all the lines down and verify integrity.

 

Thanks, I got as far as behind the glove box and see the white line coming across from the left towards the center of the dash area and connect to some sort of round hub with other black and gray lines behind the glove box, the continues under the black box where I can't follow it. Will have to remove a black panel I see when laying in the floor looking up to see if I can trace where it goes.
I opened the hood and did not find anything white going to a heater hose. I do see the heater hoses going to the firewall, but nothing is connected to them other than a red line about a foot or so from the firewall. I did see a gray line like the one connected to the hub in the engine bay, but did not think to check what it is going to.

 

Get your head (or your camera) underneath and look up.

That "hub" is an inline coupler for the vacuum hoses.

Follow the WHITE hose, see where it goes. Find where it connects to the vacuum motor and see if you have steady vacuum there when in recirc.

 

ProjectSHO89, is there actuallyl a vacuum motor on the V10 gas engine? I thought the vacuum was off the engine somewhere?

 

The black goes to the vacuum source, the grey to the hot water valve and white to recirculation door. In the dash behind the EATC is a vacuum controller, My hot water valve would not close on recirc setting, ended up splicing the recirc and hot water valve vacuum hoses together to the recir door vacuum conrtol.

 

The "vacuum motor" (Ford's name) is the vacuum-operated actuator. The actuator than is connected via a linkage, usually a bellcrank, to the actual movable door.

 

Recirculate door, and vacuum motor on exterior firewall side of blower box.

 

Hi Folks, I have not been able to get to this for a long while due to lots of life changes. I am now attempting to dig into this.
I tried the vacuum leak testing all the way from hubs up and round all visible and some not so visible vacuum lines with engine running and using the carb cleaner spray. No rpm changes.
I pulled the white vacuum hose behind glove box from the cluster hub, visible one in pics above and it has vacuum there on the white when in recirculate.
I pulled the blower motor and replaced with new motorcraft. I am getting more air on high now, so old motor was weak. Lots of black dust came out of motor on bench...no idea what that was about.
While blower motor out, i checked behavior of the recirculate door. When turning on heat, the door closes toward cabin. When cold on, door swings partially open, I would say half way out. Turn on recirculate, and door still remains in same half way out position.
I can move the door easily by hand up or down. When raising the door all the way up where I think would be the recirculate position, I can see the vacuum motor. Was hard to see how it operated as I could not get in the right position to watch it and prop the door open. However, seems the rod had a lot of play. Not sure if that was normal?
Now the question, how to access the vacuum motor? Can I remove the panel behind the glove box, the one with the screws facing you (large rectangle panel) and assume behind that is the heater core? If so, can it be removed and then access the vacuum motor?

 

unfortunately, this system isn't directly plumbed into the intake like most vehicles. The system has a vacuum canister (pass fender) that holds a small reserve of vacuum for the system. Eventually you are correct and the lines will feed the intake. But there is alot of it, and you are unlikely to trigger the classic RPM rise response when spryaing near a leaking vacuum line.

For under $15, I bought replacement vacuum line on Amazon. I recommend you do that, then simply replace all the vacuum lines and fittings. It'll take minutes and honestly is a net positive considering these lines are 20+ years old. I had a tiny leak that only occurred when the outside temps were <60F. Leak sealed up after a few minutes of running, or when it was >60F outside. I never found the leak. I replaced all the lines and my issue went away. The hassle of chasing the leak drove me crazy.
carbon dust and whatnot. sounds like you got your money worth. go ahead and pull the new motor back out. Take a garden hose and spray the evap core (inside, to the right) out with a garden hose. It's exactly like a radiator and most likely very dirty if not outright clogged. Mine was clogged with diesel soot and dirt. Almost zero airflow across. I sprayed it with the hose and a degreaser. The water will drain out the weep hole in the bottom of the airbox. To the passenger frame rail. Just check the pass floorboard periodically to ensure it isn't leaking into the cab.
door moving up blocks the airflow from outside and allows you to see into the dash interior (behind glovebox-ish). door moving down opens up the cowl suction. this recirc door should only "shut" when you hit the recirc button (Auto AC) or put the switch to Max AC (manual AC). It shouldn't move otherwise. the recirc door is mounted horizontally and at top of the airbox. You can snake you hand through it and into the cowl.

it almost sounds like you were looking at the blend door. was it positioned vertically and near the bottom of the airbox? It usually has a small strip of weatherstrip. If you pull the glovebox out and remove the handful of 6mm screws, there is an access panel that lets you view it.
up a few posts is a pic of the vacuum motor. not easy to access. My blend door never truly shut...so some heat was always coming across. Which is why I think isolating the heater core water loop on these Fords is so important for max AC temps. It can't heat up the AC if the water isn't flowing.

 

I have a 17 F250 that the recirculate door is somehow stuck open allowing outside air into. Like someone else stated, I don’t hear any movement when you turn the button on/off. I’m told that model truck requires the entire dash to be removed to fix this issue. I live in the Deep South. I have zero need to allow outside air into the cabin and am not looking to deal with the vacuum lines mentioned above. Is there a way to block the airflow from the outside before it circulates under the dash?

 

Great write-up Tylus.

I must say, this post has everything I have been looking for to rebuild my 2006 F250 HVAC system.

greasyelbows