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  1. #1
    Jr. Apprentice
    Join Date
    Feb 2011
    San Diego CA

    Default noise under dash 99 Suburban

    I hear a noise under my dash while the engine is running on my 99 Suburban. Sounds like something is pressurized. AC/heater is off, fan off. And when I shut the motor off I still hear it for a few seconds and it sounds like it is depressurizing or vacuum is being released. reminds me of vacuum switches on my dads old 70 Mercury Marquis wagon.

  2. #2


    How's the truck running? It sounds like it could be a loose/damaged vacuum line, but I can't think of where it would be under the dash. Check there and under the hood - ya know how sound travels...

    Good luck,

    1999 Chevy K2500 Suburban 350
    K&N, reworked cai, Thrush cat-backs
    Vinyl, cranks, floor shift, and rear air!

  3. #3
    Jr. Apprentice
    Join Date
    Feb 2011
    San Diego CA


    It runs good. It makes this depressuring sound after the motor is off. Hard to describe sounds like a fan running or something

  4. #4


    Check for a busted vacum hose somewhere might even be a heater hose broke or maybe even a wiper hose just do one thing at a time so you can eliminate it and get to the next one good luck.
    Canopies | Portable Shelters | Pop Up Canopies

  5. #5


    did you get it fixed alan? i have the same problem

  6. #6


    I've had restricted lines in my radiator make weird sounds. Does it happen to be coming from the heater core area? You might consider a radiator flush if you haven't had one in the last 3 years.

    Other than that, check to see if it's an auxilliary fan spinning down (bushings will occasionally wear and cause light whining).

    2006 Vortec Max 1500
    -Custom Tune (389HP 440 Ft/lbs Trq - Dyno'd) | Volant CAI | Magnaflow Dual-in/out Exhaust w/3" stainless pipe tips | Fully Built Transmission w/ Red Eagle Clutches & Kolene Steels w/ Corvette Servos and Stage2 Shift Kit | 35K Tranny Cooler | Mobil 1 | Royal Purple Rear Diff
    -Spray-in Bed Liner
    -Premium Sound w/lifetime Satellite Radio | Leather | Sunroof | Heated Seats
    -Limbstriping from USING the truck (those are badges of honor)

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