AC/Heater/Defrost switch erratic

Usually when it blows out the defrost only you have a vacuum leak to the controls. Most likely under the hood on the pass side.

Am I looking for a broken or cracked hose? These are the hoses that are approximately 1/4" in diameter correct?

Thanks for your post. It has me starting somewhere.

Harry

yes, they usually go in through the firewall onthe pass side. Sometimes they are smaller than a 1/4 inch and made of plastic. If that is the case and its broken, you can use a rubber hose of about a 1/4 inch as a connector of sorts to fix the broken place.

Thanks for taking the time to reply to my post. It wound up being a cracked vacuum hose in the REAR of the vehicle. The E350 was set up for rear air as an option and the hose was run to the back but connected to nothing. I cut the hose before the crack and plugged it and everything is fine. That was a fun job.

Thanks again,

how did you find it?

I could not find a hose coming out of the firewall, so I dismantled the dash and found the plastic hose. I followed the hose until I found the crack which was in the rear of the van. After finding it lead to nothing, I cut the bad section out and plugged it. Voila. 2 1/2 hours later...done. Knowing what I know now, it could have been done in 15 minutes as no dash disassembly needed to be done.