I have an interesting problem. My 2001 E350 van's factory rear A/C is not working. Front A/C and heat is fine. Regardless of front control position for rear, heater stays on all the time unless I turn it off with the rear control. No air is blowing from the rear A/C vents, only from the rear heater vent. This isn't a big problem right now, but will soon be an issue. I use this van for my sales route, carrying a lot of temperature sensitive snack products.
I don't have an owners manual, and the Haynes manual has no info at all regarding the rear A/C.
I'm open for suggestions!

 

Hot water shut off valve stuck open, vacuum hose off etc. The heater will overcome any cooling done by the evoprator.

 

Hey Rik here's a quick few bits about your rear heater & A/C Unit:

First image is of your same unit, that you'd see behind your interior panels---as you already know this is located in the left rear of the cargo/passenger bay:



Locate and follow the blue vacuum line running---it should be visible ^^ there.

Here's what I think is happening, shown by these following images:

First shows a door highlight in yellow that is closed by default or lack of vacuum. Air is directed over the heater coil even though the front or rear A/C controls are set to Cool.



Now same door opened when vacuum is applied typically when A/C is called for---its assumed the Temperature Controls up front and rear is set to cool or cold.



If this door doesn't open the evaporator might still be properly working (per the rest of the system) but your rear vents will feel nothing but heat.

Here's the vacuum motor installed on a rear heater case, not yet installed but missing its evaporator:



Most likely somewhere along that blue vacuum line's run is a leak OR the vacuum motor itself has failed. You need to first check operation of this motor/door assembly.

Here's a diagram of the complete vacuum heating/cooling system which might help explain how all this works

HTH

 

I'm not sure about 2001, but E Vans in the mid 90s had a vacuum connection in the front instrument panel that controlled the rear blend door or coolant valve.

It's been a long time, so I don't exactly remember how it worked without seeing a diagram. I ran into a few of them where the line split at the tee causing the symptoms you describe. I believe the line was Blue, as JWA mentioned, and was the supply for the rear controls.
The Tee is under the access cover on the top of the instrument panel. Even if the connection is intact, it's a good place to start testing.

 

lsrx101 you're correct and there is another connection or splice for that blue vacuum line at the bottom of the B Pillar post, drivers side about 6-8" up, typically stuffed inside a wire chase formed by that pillar.

FWIW the instrument panel access location is here:

 

Looked at the dash access, all seems to be working there. I didn't find the 'T' connection, will check on that later.

 

Have you yet located and/or checked the very rear line and motor/servo?

I do notice a thermostatically controlled expansion valve on the evaporator I removed from my factory rear unit---that is another possible source of your situation although I'm still going with my guess its vacuum related.

 

I haven't had a chance to look at the rear line or servo/motor yet. I'll have time this weekend to do that. I have to remove all the shelving on that side to get access. This is more time consuming than difficult. I have decided that if this requires too many $$ to fix, I will find a way to position the door to the cool side. I don't use the rear heat much at all, especially now summer is almost here. I'll also check the expansion valve too

I really appreciate all the help you have offered! I had absolutely no idea where to begin to trouble shoot, but I guess that was pretty obvious. I also agree Haynes manuals are pretty much useless, but when it is the only available reference available ona short notice, you go with what you get.

 

I don't mean to bad mouth the Haynes stuff too much---I've been frustrated by them a few times---it seems whatever problem I had was a bit too specific and not covered or addressed. Yes they're good if that's all you have although if you'll be keeping this van and doing or wanting more of the DIY maintenance I can recommend eBay as a good source of gently used factory manuals.

I have a few including a full service CD-ROM I lucked into a long time ago. Typically this would be a huge two-volume notebook so my version is easier to use but not very portable. EVTM's are invaluable to me, here's two you might consider: 2001 Ford Econoline VAN Factory Wiring Diagrams Manual | eBay OR: 2001 Ford E-Series (Econoline Van) Wiring Diagrams | eBay Probably the only real difference is the price---most of them will show signs of use.

I hope we've been of some help----its difficult diagnosing from so far away!

 

JWA, you have been an immense amount of help! I tore into it this afternoon, found everything seemed correct, with the exception the door wouldn't switch. I had good vacuum to the actuator. Removed the blower motor to get limited access to the door, I 'think' it is broken where to actuator attaches as the door can be positioned with my fingers.
I did a quick fix by positioning the door to direct the air flow to the evaporator, and putting a couple of screws through the housing into the door to hold it in the cooling position. Pretty quick fix, and since I really don't use the rear heat much at all, I am happy.

I again want to thank you and the others for all the help and suggestions. I even got it all back together tonight. I was really expecting a L O N G weekend. I can only guess what it would have cost to have this done at a shop. Not against shops, but if I can do the repair myself, I like to save the $$$.

 

That's good to hear Rik---its nice being of help!

Send me some reps!

 

JWA, you got your rep points. Thanks again.

 

Thanks Rik!

When you get this all sorted out and working properly again please post what you found and the repairs you were able to DIY. I'm interested and maybe someone else can benefit too later on.

 

Not sure I'll ever try to sort it all out. This is a work van, was actually totaled out a few years ago due to hail damage. Colorado allows you to retain title and license. The damage is purely cosmetic, but the repairs exceeded the book value. As I said earlier, I could not feel any connection to the actuator (vacuum server) to the door that switches air flow between the heater core and A/C evaporator. I did feel what appeared to be a broken tab of sorts, which I will assume is where the actuator connected. Since the door moved freely, this makes sense. To remove the actuator it looks like I'd have to remove the entire rear system. Two screws hold the actuator to the chamber, but one is in a location that I cannot access. And since I really don't need the heat in the rear, and I do plan on driving this van into the ground before replacing, I'll stick with this repair. That, and removing the shelving and interior panels are a pain.....

 

This is a very heplful post. I think I am having the same problems. only the pictures are all missing. Any chance you could repost the pictures. Thanks in advance.