Chrysler Repair: Lebaron: no cabin air controls/always defrost, manifold vacuum, vacuum line

Question
Whatever heater control button is pushed, everything blows out the defrost. I have checked for vacuum a leak from the brake booster to the firewall and at the back of the control panel. I can't get to the vacuum line under the dash after it comes thru the firewall. Do you have any suggestions?

Answer
Hi Don,
You already have the control panel out so the first thing to do is see if you are drawing a vacuum on the black hose on the #3 port of vacuum harness. That is the line from the firewall that also has a check valve in it to hold the vacuum should the manifold vacuum drop due to flooring the gas pedal. If you aren't drawing vacuum then there is a crack somewhere between the branch point at the power brake canister and port #3 or the check valve is stuck closed. If you are getting vacuum then depending upon which distribution button you have pushed you should find vacuum on one or more of the other 5 lines that exit the control switch. Those lines are attached to three different vacuum door actuator that control: floor-defrost, panel-floor-bilevel, and outside-recirc air. Two of the three actuators are on the left hand end of the unit (except for the outside-recirc actuator). The defrost-floor actuator has a single yellow hose, The various other distributions are governed by the regulator that has red and brown hose. (The light green/dark green hoses are for the recirc/outside actuator). If all you get is defrost, it probably means that you don't have vacuum getting to its actuator on the yellow line, either because you have no vacuum coming into the unit from the firewall, or there is crack in the yellow line from the vacuum switch to the floor-defrost actuator, or the defrost-floor actuator is stuck.
Roland