The hard part is identifying where the problem is. Listen, the vents are run by vacuum from the engine. Try looking under the dash to identify any vaccum lines that are damaged. Also, follow them from the controler to their destination. Then you will need to follow them through the firewall to the engine to see if there is a problem. Also, with the engine running, listen for hissing sounds that would indicate a leak.
I wish I had an easier way to tell you, but this is it.
Let me know if you have other questions.
Thursday, April 9th, 2009 AT 9:25 PM