hvac question

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500, 472, 425, 368 Discussion, hvac question in Cadillac Engine Discussion; Hi all, I havent been here for a while and ran into a problem you might help with. I own ...
  1. #1
    andy-gts is offline Cadillac Owners Member
    Automobile(s): 68 and 70 eldorado
    Join Date
    Sep 2009

    hvac question

    Hi all,

    I havent been here for a while and ran into a problem you might help with.

    I own a 1968 cadillac eldo with ac blowing cold , but blows out the vents only in park or neutral . when in D, or low the system blows out the floor and defrost vents...

    could this the the neutral safety switch with a leak....

    any brainstorming would be helpful....

    thanks in advance


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  3. #2
    jayoldschool's Avatar
    jayoldschool is offline GM RWD V8 addict
    Automobile(s): 81 FWB D'Elegance coupe
    Join Date
    Sep 2006
    Ontario, Canada

    Re: hvac question

    It's a vacuum leak, for sure. Probably on the rear of the control head in the dash, but check the line on the intake.

  4. #3
    OldBlue68 is offline Cadillac Owners Member
    Automobile(s): 1968 Sedan de Ville
    Join Date
    Sep 2010

    Re: hvac question

    It probably is a vacuum leak. The system is designed to send vac to the idle speed up diaphragm on the carb in P/N. You might try pinching off the vac line to the P/N switch first. Check any other vac connections that are easily accessable too.

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