ok guys,check engine light came on,took it to the shop and they told me it was a bad charcoal a.k.a vacuum canister funny part is i go to leave there and turn on my a/c and the vents arent working.still blowing cold but only coming out of the defroster vents.well what i want to know is,is it connected the vac. canister and the vacuum for the a/c controls? was that just a fluke,they hook up the code machine tell me my problem then the vents quit? i checked every place he had his hand and i didnt see any evidence of anything lose in those 2 spots.. any help is appreciated.i got the new canister today from ford,and will be putting it on this wknd..thnx bb sorry forgot to mention it is a 1997 mustang 3.8 automatic, a/c

What year Mustang do you have? Or whatever kind of car you own?

Check the vacuum line that goes thru the firewall on the passenger side. It leads to the Heater control panel. It may have been disconected.

ok that firewall vac. was connected and nobody has been in under the dash,any other ideas? i bought a haynes maual today which was no help anybody got a diagram of the vac. line setup for the a/c contro;s? i mean where they run from after leaving the switch? or any others ideas welcome..thnx bb

Isnt the vacuum canister a little cylinder thing? If so when my check engine light came on for that I just took it out and cleaned it, disconnected the battery and the light hasnt came on in over a month.

well yeah it is and i just bought a new canister,and it fixed the check engine light,but im still left with a/c that works but only blows out of the defroster vent,as suggested i checked the vac. line going in thru the firewall but it is connected and when it went out nobody was under the dash,so im trying to figure out what else to check to make the vents work..i mean im assuming for now that it is a vac. thing,hell for all i know ithe switch could have just went on the fritz all the sudden any suggestions i`ll take em ...thnx bb