I am not sure were this should be posted, if the switch that controls the different vent settings/ac works but only blows air threw the defrost vents what is the most likely problem? The A/c even works and blows cold and the fan speed switch works great, but the one that controls the Defrost/ AC settings ect only puts air out of the side vent/ ones under the windshield. No matter what setting it is placed in.

 

The vent control works off of vacuum. You have a vacuum leak. Good luck...

 

Does anyone have a diagram of the vaccum setup for the switch my CEL came on as well and the things running a a bit rough so that would make sense I just need to know where to look. It looks like the yellow lines running to the switch go back behind the glove box.

 

Many people on crownvic.net have had this problem in the past and it usually winds up being the blend door or the blend door actuator, both require dash removal to fix.

Could be a vacuum, but you'd think you'd be having other issues besides airflow problems.

Get the codes read and see why the CEL is on, maybe it's a simple fix.

 

What year and motor do you have. On my girly's ride its a single, thin, hard plastic line (about the thickness of a 14 or 18 gauge wire) going from the hose/vacuum junction block by the brake booster in the engine bay, to the left side of the fire wall and into the dash. Over time they get brittle and break causing the exact issue you are having. The "no vacuum" setup for the vents is all the vents closed except for the defrost, which is the exact problem you are having.


a CEL would not come on for this AC issue. It is probably a different issue. Go to your local auto parts store and have them read the codes. With that code you can search around on the intertubes and find a good starting point for the CEL issue.

 

3.8 I fixed the switch the one vacuum line running from the firewall to the intake under the hood was disconnected, I tried to have to local parts store pull the codes but none of them will do so being as I guess last year CA made it illegal for them to do so.

 

I had the same thing on my 94 and figured out it was the vaccum line. The think hard hose going to the brake booster had come loose. Plugged it in and it worked fine. Only had upper vents or defrost. I don't remember. Good Luck!