JTEXFISHER aka Harold Thank you so much for the pics the access panel on the top of the dashboard was where my husband went after your post and found one of the vacuum lines unplugged, Your post kept us from a costly repair and you have my thanks.

 

I reread my post and see that I missed something important... It's between the interior portion of the HVAC unit and the firewall. You can take stuff off all day long under the hood and you'll never find it.

 

Well now you tell us this!

This has me very intrigued now----I'll have to dig around under my dash since I already have some of those lower trim and structure pieces removed.

We'll find and photograph this thing yet!

 

You're just going to get yourself frustrated unless you have x-ray vision. If you do, why are you using it on the car?

 

I don't believe I'll be pulling the air intake to install a canister behind it, too much trouble dealing with that, yet I'll remove it to replace some of it so it doesn't come apart easy anymore, not sure the best location for the vacuum canister.

 

Hmm as I ponder this I conclude such a super power would make bikini watching more interesting yes?

I'm going to tear into my lower dash today or Wednesday, photos of what's found---or not--along the way too. My E250 is an '03 but should be similar all the way back to '97 I think.

Stay tuned!

 

My 1997 E-Superduty developed this Defroster issue a couple weeks ago. SUper annoying to deal with because its the chassis of oy 1998 GBM 31' Class C motorhome. The HVAC is part life in a motorhome.

So just to recap....

The hidden Vacuum canister is what fails (most of the time) and adding a new one and running a new vac line to the top of the dash, bypassing the old line that obviously goes to the vac canister, as shown in the pics is the fix. This is a great solution and I am going to put it in play next week.

Has anyone pulled the black hose off the connector at the top of the dash and put a vacuum gage on it to see what's happening? Just curious is all.