Max AC/ventilation fan problem?

[JohnMcIntyre]

If I crank up the ventilation fan to the highest position (4), with max AC enabled on the dashboard climate control, the two vents on the passenger side seem to have a a lot more rotational style noise (only way I can describe it) compared with the driver's side vents.



Funny thing is, that the noise is only present when max AC is enabled Levels 1 and 2 are no different - one of the few parts of the truck that's not been bombed Everything else meeting and or exceeding expectations.



Aybody come across this before? Any thoughts/suggestions welcome!



Cheers!

 

[roadranger]

I think what you are hearing is recirculation noise. When in Max A/C the fan recirculates the cab air, with the suction under the passenger side of the dash. Higher fan speed creates more noise.



My 2500 does it, so does my work Durango.

 

[nps]

What roadranger said.



Kinda like holding your hand over the nozzle of your shop vac and listening to it wrap up, except in this case the nozzle end is inside your cab and closer to the passenger side.