94 Century Heating question.

Hello, I've got a 94 Century with the 3.1 in it. The problem I am having is that with the heat or ac on directed at the floor any time I accelerate the air flow is diverted to the dash vents or defrosters then when the gas is let off the air flows go back to the floor as it suppose to. What I think it is and I would just like some one else's input before I tear the dash apart, is it possible that the actuator that controls the damper is weak and needs to be replaced. Or should I look some where else before tearing apart the dash? Any input would be appreciated.

Thanks

You may have either a vacuum leak or low engine vacuum. When you accelerate engine vacuum goes low or towards zero. The HVAC system uses accessory vacuum from the intake system to control the vacuum operated actuators. Inspect the vacuum line from the upper intake manifold and where it goes into the firewall. Then in the dash area. Run a vacuum check if necessary to make sure it is in specs.

Also, inspect all other vacuum lines at the upper intake. Plus you may have a vacuum storage container in the area of the engine compartment before the accessory vacuum heads into the cabin.

Thanks, I will look at the vacuum system first. Any idea what it should read when testing it?

Thanks, I will look at the vacuum system first. Any idea what it should read when testing it?

Using a standard automotive vacuum gauge (0-30 hg) you should read in a range of 15-22 in. hg.

Thanks, I did find a check valve bad on a vacuum line and also a few cracked hoses. Replaced and is a lot better but it still wont hold position 100%, but I'm not sure if it ever really did. Thanks for the help and will hook up a gauge over the weekend to see what I have. If it continues to drift as it is now I dont think its worth the trouble tearing the dash apart.