Vent duct noise
 

Hello,

I have an 01 Concorde. One issue that is occurring is that when operating the blower, there is a noise coming through the vent duct like a relay is opening/closing or a damper is opening/closing. The air flow does not seem to be affected but the noise is continuous. The noise stops if I stop the blower and changing the air flow direction (defrost, low vents, mid vents, mix) makes no difference. I'm not sure if something is failing or just needs lube/adjustment.

Any thoughts would be appreciated...

Bill

The system has three doors in it. One door, called the "blend door" changes the mix of heated or cool air to change the temperature of the air coming into the car. Another door is called the "mode door" and it directs the air out the floor vents, the dash vents or the defroster, or some combination. The third door controls where the air comes from to go into the heater, either from outside or from inside (recirc) the car.
If one of those doors is activating, you should be able to determine which one by how the heater is behaving.
The operation of the doors is actually controlled by the body computer based on inputs from the control panel.
Don't know whether any of that will help you track down your issue, but it may.

Vent Duct
 

Thanks, based on your post, it probably is a door opening/closing continuously. I'll check which one using this troubleshooting info.