Chrysler Repair: Grand Caravan Vacumn Leak, vacuum line, vacuum leak

Question
Is there access to the area without taking the dash and or the center console apart?
Mark
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Followup To
Question -
Roland,  my 1994 grand caravan has a vacumn leak under the dash.  When I accelerate the blower will switch from the vents to the defrost.  I have already replaced the check valve on the line from the brake booster to the firewall.  I can also sometimes hear a whistle from under the dash.  Is there a part which usually goes bad which causes this problem?
Mark
Answer -
Hi Mark,
Yes, the vacuum line continues thru the firewall and on to the mode door vacuum switch which then directs the vacuum to move the doors and redirect the air. You have a leak, probably in the same hose, somewhere from the fire wall to the switch. I haven't worked on the under dash area of the vans, but I suspect you will find the line on the right lower side of the A/C heater housing probably in a harness with some electrical lines. It may have just become loose at the switch connection or possibly cracked. The symptom you have is consistent with a vacuum leak which reduces the vacuum to the system and then when you accelerate (the throttle is opened) the vacuum is reduced even further so the door moves to the default (no vacuum) position which is the defrost position.
It should be easy to find by ear!
Roland  

Answer
Hi Mark,
The vacuum switch is, I believe, immediately behind the control push buttons. So what you might want to do first is to reach around behind the rear of the unit and see if you can possibly feel the vacuum line coming in thru the fire wall. If you can then you could attempt to follow it by touch to see how it is routed to the control unit in the console. In addition, you will probably need to remove the control panel from the center console. In the passenger cars there is usually a bezel surronding the center console which once removed gives you access to screws on both sides of each sub-unit in the center console. If you remove the screws, you can pull the control unit out somewhat, but it will be constrained by the electrical connection, a vacuum connection, and a temperature control cable connection. But you may be able to observe the vacuum lines without totally removing the control panel. If not, then disconnect all and remove the control panel. That should give you good access to all the vacuum lines for inspection. I'm basing this on the set-up for cars in the late 80's which I suspect is not very different from your van.
Roland