does anyone know if an 06 5.4 xlt uses vacumn to run heater controls. reason i ask is if i'm at idle and change the setting it makes a noise that sounds like a vacumn valve. but if i'm driving at higher rpms it doesnt make the noise.brakes also seem to make vacumn sound at idle when coming to a stop. wondering if i have a vacumn leak or low vacumn havent check with a gauge tho. not missing and no cels

 

Yes the AC vent controls are controlled by vacuum. At low idle the vacuum has to build up to change vents...ect.. Thats why at high idle you dont really hear it because the vacuum is already built up. As far as the brakes go, thats your brake booster you are hearing which is normal.

 

Mine are all controlled by electro servo actuators in my 08. They are all like the blend door actuator.

 

I got a 05 xlt 5.4 and its all electric. Only thing thats vacuum is the brakes, evap and 4x4.