Possible vacuum leak

[yh125d]

07 Ford Fusion S, 55k miles


I picked my car up from the stereo shop today and I noticed a few things. When idling in neutral or park the rpms will drop quite a bit and bobble back and forth and nearly die Also, My brakes feel different, through the first 1" or so of travel the pedal feels very light, then gets rather heavy. Somewhat akin to the feeling of having air in brake lines. Third, I can hear a hissing noise coming from under the dash near the pedals that changes when the brake pedal is pressed and released. I'm pretty sure the installer just knocked a vacuum line loose somewhere under there and its no big deal, but I thought I'd run it by you folks and get some ideas

I have checked the battery and it is at 100% and the alternator tested fine, so I'm pretty sure its not an electrical problem like I first thought.

The symptoms occur while the stereo is completely powered off, so I don't think that it is causing anything either

Would anyone know where I could find a vacuum system diagram for my car online to familiarize myself?

Thanks

 

[Vette73]

I have not been a full time tech for a while so I don;t know the Fusion well.

But on older cars the Cruise switch had a vacuum line go to it, but most cars I thought did not do this any more but you can check for that.
Also older cars used vacuum in the AC/Heat system to control the mix controls.

Other then pulling the cover above the pedals and looking ans also pull the radio to see what behind its hard to say.

 

[yh125d]

Update: Took it back to the stereo shop and they confirmed that it was a vacuum leak. They couldn't find it though, so they sent me to an auto shop in town to look at it. Turns out they drilled a hole in my power brake booster I guess when they were running my amp power wire. 5 more days to get it here, another day away from work next week to get it installed, and I might have a fully functional car. FML