2004 E.B. Expedition rear ac clicking

there’s a click in my wife’s expedition coming from around passenger side 3rd row when the AC is on. when we turn the temp down a little bit the lciking goes away.
any idea what this is??
Thank you!

Probably a defective auxilary AC blend door actuator.


The blend door actuator is what mixes the cold air with the warmed air to achieve the desired temperature out of the vent system.

That’s probably why the noise stops when you adjust the temperature.


Failures of those HVAC actuators are a pretty common complaint here. I’m not sure what you mean by “third row”, but if you mean the third row of seats, that’s a good thing as the failed actuator isn’t under the dash so presumably will be easier to replace.

In years past the HVAC actuators were just cables you controlled with a lever. They rarely failed. But with the more advanced functionality, gadgets etc, buyers seem to want, to provide the proper airflow routing to all parts of the interior they had to switch to electronic actuators, stepper motors I think is the most common version, and those haven’t proved nearly as reliable as the cable actuators.

As an example, the cable actuators in my 20+ year Corolla system work as good as new and have never needed any repairs, same for the ones on my 40+ year old Ford truck. Never needed any repairs in 40+ years. Of course the air temp isn’t quite as consistent throughout the cab on the 40 year old Ford truck as newer vehicles. It’s a trade off I guess.

There are two blend door actuators in the rear unit, one on top and one on the side. To know which one, have it all apart and be there to listen and feel .