Chevrolet Repair: heater/ac vents, heat vent, vacuum tank

Question
  I recently replaced the selcter switch that controls selection of heat, vent, a/c, defroster, etc.  Since then, any selector position I choose directs air through the defroster vents.  Is it a bad switch, did I install it incorrectly, is there a new problem?  Thanks for any help.

Answer
Hello Robert, You let out the part of what kind of car you have, oh well. Most cars have vacuum controlled switches, test to make sure you have vacuum at the switch with the engine running. If there is no vaccum then locate the leak in the vacuum line, most times it is near the intake manifold or at the vacuum tank.

Hope this helps

Mark