1979 z vacuum issue

Discussion in '1978 - 1981 Specific' started by rodebcada, Apr 22, 2020.

  1. rodebcada

    rodebcada 79zrod

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    Just had the engine bay detailed and painted. Now the ac/heat controls wont work. Thinking its a vacuum issue. Anyone have a pic of hoses that should hook to the vacuum ball and does the vac ball play a role in the transmission modulator. Trans started to shift hard. Never had any issues before. Only has 7400 miles

    Thanks
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    The vacuum ball doesn't affect the transmission modulator. The modulator has its own line off the intake or back of the carb and directly down to the tranny. It is commonly pulled loose when messing with the engine. Start there by looking at that line.
     
    Last edited: Apr 25, 2020
  3. Zspoiler

    Zspoiler Veteran Member

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    I would also buy an assembly manual for you car .They are around $25.00 .It might help you with any other issues down the road ,Good luck to you.
     
  4. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    Behind the carburetor there is a vacuum tee in the intake runner. The hardline goes to the transmission vacuum modulator and the rubber line goes to the ball on the HVAC box. If both are not connected, you will have the problems you describe.
     
  5. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    There's also a little vacuum line (which looks like a heavy wire) running from the vacuum ball through the firewall a few inches to the passenger side of the distributor.
    That's the source of vacuum for all of the various HVAC actuators.
     
  6. rodebcada

    rodebcada 79zrod

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    Bingo! Cracked hose at the vacuum tee and the small line to the vacuum ball had fallen down in behind everything else. Hooked lines back up and rough idle, transmission hard shift and hvac issues gone. Thanks guys. Best 2nd gen site out there.
     
    hossz28 likes this.

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