Question about 1998 Ford Explorer

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A/C and Heater vents.

I have a 98 explorer sport, 4.0 6cl sohc. I've been having issues with the A/C and heater. The problem is that the vents are not opening properly. When I turn the knob to select either heat or ac the air only comes out of the defog/defrost vent on dash. It started last summer but I didn't worry about it too much because the air still came out cold. I did however notice that once it started to get cold this winter, the compressor still kicked on when I was using the heater. I finally started messing with it to see if I could fix it. Not knowing anything about the system I just changed out the vacuum switch to see if that's why the vents were not opening and closing the way they're supposed to be. But that didn't work. It's warming up again here in AZ and now the air only comes out hot. Can anyone help me?

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  • shadoboy93 Feb 03, 2009

    What if there seems to be no vacuum?

  • shadoboy93 Feb 03, 2009

    The hoses and the canister is there where you said. I am not feeling suction or air leaks at all. I pulled the black hose off and feel nothing. Is there something else I need to replace?

  • shadoboy93 Jul 10, 2009

    still working on it. I got it to blow cold are by manually adjusting the blend door and rigging the vent door to blow from the front facing vents.



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You have a vacuum leak. The default postion(no vacuum) is defrost and heat. Check the small black vacuum line coming out of the firewall on the right side near the ac evap and heater core. Trace it back to intake and make sure it has vacuum there and there are no leaks. You should also see a vauum canister when u trace it back,this is the reserve so u have enough vacuum to keep it from changing from floor to def when accelerating.

Posted on Feb 03, 2009

  • Chuck Martin
    Chuck Martin Feb 03, 2009

    You have to have vacuum on the black line in order for the system to work. Have you traced the line back? Is it broken maybe?

  • Chuck Martin
    Chuck Martin Feb 03, 2009

    Can u trace it back to where it hooks up to the intake manifold? Unhook it there and see if u have vacuum.



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