My 06 E350 extended developed a vacuum leak about 5 years ago. Before that rear AC was great and would freeze you out. About the same time rear AC stopped as well. As I was using it as a cargo van for work I just did not worry about it as the front worked great. Got the vacuum issue taken care of last year but wasn't driving it so didn't really worry about the rear but it did seem to blow warm air.
Today I tore into it as I am working on selling it. Vacuum door is working correctly when tested plus air does come out the roof vents. I was only testing at idle, but the evaporator did not even seem to get cold. Front AC again no problem. Tried to follow the lines but did not see any kind of valves that could be a problem.
Still cool here so a little harder to check. Maybe I just need to turn it on and run it down the road to see what happens. Another little bit of info while I had the vacuum I never saw any water dripping from the rear, just the front. I guess it could be a clogged line, if there is such a thing. Any help would be great.
Thanks,

Stephanie

 

My guess is the rear A/C control valve for the refrigerant is not operating properly. These are often vacuum operated, so it may have been inadvertently disconnected during the vacuum diagnosis and repair.

 

Thanks Ian, that makes sense as it seems to have started with the vacuum leak. I went out and looked, but have not located the control valve yet. Do you have a clue where it may be located at? I am going to keep looking but your input is very welcomed.
Stephanie

 

Thanks again Ian. Van was sold yesterday and during the test drive I think it was working so all is good. Have a great day.

 

 

I am not. While I have a reasonable grasp of the principles behind how these systems work, the details of each vehicle tends to be unique and I haven't had a chance to really dig into my own van yet.

 

In '05 Ford's A/C (maybe only in the E-Series" seems to cut out under acceleration, returning to normal air distribution once a steady throttle is re-established, a design feature.

The rear air distribution while in A/C mode will always be through the roof vents, only in heating will or should the air be exhausted through the floor vents. From your description all seems normal.

HTH

 

So in an effort to eliminate possibilities and after seeing another poster's comment about the possibility of Auric's hand-made PVC vacuum reservoir tank having inssuficient volume, I purchased the OEM reservoir from Ford and attached it to my bnypassed set up now that it is under the passenger side kick panel (thanks to Auric's bypass solution). With the OEM tank attached, the rear a/c non-switching behavior until I let go of the gas is gone. In that if I'm on the floor setting and the rear is functioning on the floor vents, when I switch it to AC, the roof vents become activated after a few seconds without me having to let go of the gas as I was having to do with the PVC pipe reervoir tank. I did not have a change to validate that the PVC tank was air tight previously as I had used the liquid paste pipe thread sealer when I first built the pipe, but I will do that this weekend. I am leaning towards agreeing with the though that while there maybe sufficient volume in the 1' length of 1.5" pvc pipe to solve my front vent switch problem (and the check valve), there is not enough volume for the vacuum needs for the full length of the van to activate the blend door in the back. Will report back with the air-tight test on the pipe and also will experiment with building a bigger tank with a bigger diameter PVC or longer length, whatever is more convenient in the placement. Either case, I thankfully proved that I don't have any rear a/c Actuator or blend door issues since the air in the rear will swith from the floor to the roof vents using the OEM tank.

JWA, now that I've switched the check valve and the reservoir, the front A/C is not cutting out on me from the forward facing vents to the defrost when I am accelerating at all when I accelerate and while accelerating it will also switch from the front defrost to the front ac vents. The rear a/c is swtiching great also while using the OEM tank, so I'm thinking that there isn't a normal behavior for the 2005 E series to need to get to normal acceleration for the A/C to switch properly. It's seems like it's just a combination of possible vacuum/actuator failure possibilities that have to be necked down until you figure them all out.

Jeez, what a PITA, but thanks to you and other posters who have trailblazed this and other issues on this forum such that I'm a little less singed than I otherwise would have been while trying to figure this out on my own!! Thanks!!

I will report back on my final troubleshooting and if Ican't get things to work with a larger diameter pipe tank, I will bite the bullet and get the OEM tank to clear this once and for all.

 

deleting this post as it double posted my post above.

 

I'll be interested in your results FDDjr1!

 

So I was able to test how air-tight my PVC pipe reservoir was this weekend, and it was air-tight. So it looks like I might be a bit small in terms of capacity to activate the floor to roof vent change in rear a/c without letting go of the gas. Again, it works perfect with a new OEM tank I tested the byspass system on last week. Had to help my brother with some brakes yesterday so didn't get a chance to build a bigger diameter (more volume) pipe tank so will see if I find some scrap 2" pipe at my dad's to test on his or if he doesn't have any available, I may bite the bullet and buy the OEM tank online for $7-10 less than the local dealer price of $41...I am just sad to have to pay $30 for a piece of molded plastic, and I may have to do the same repair on my dad's 2005 e350, so I may perservere and build one. I will let you know if the bigger PVC tank does the trick if I can build it.

 

Do let us know what you discover---could be helpful to others as well.