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i ain't rite
Joined: Mar 2005
Posts: 65,564
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From: Marlboro Mental Hospital.
bad vacuum line from the vacuum manifold on the firewall to the inside of the cab. look for a broken or cracked white 1/8 vacuum like going from the firewall to under the ac/heater box.
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Joined: May 2015
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Seems like every truck I look at that line is either broken or missing. I've also seen my fair share of zip ties holding an actuator open..also done it a time or two myself..
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its weird because it seems to skip over floor and go right to defrost or vent.. floor setting just blows out the defroster vent.
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Joined: May 2015
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I believe the one in the engine bay is for fresh or recirculate.
You may check the one under the dash and if nothing else pull the HVAC control and make sure all the lines on the backside are in good shape.
All it takes is a rat at one time a decade ago to nibble a little hole.. Maybe your HVAC control unit could also have an internal leak or a crack.
You may check the one under the dash and if nothing else pull the HVAC control and make sure all the lines on the backside are in good shape.
All it takes is a rat at one time a decade ago to nibble a little hole.. Maybe your HVAC control unit could also have an internal leak or a crack.
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Joined: May 2015
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If you have or can borrow a vacuum pump you could route it to your HVAC system from under the hood and it's quiet enough you could probably hear where it's leaking.
If you have some know how an old fridge compressor makes a great vacuum pump.
If you have some know how an old fridge compressor makes a great vacuum pump.
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the actuator at the bottom of the box does move and I noticed that it does not stop mid way where floor would be. It moves all the way forward or all the way back.
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Joined: May 2015
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When I got my 89 one of the studs for the vacuum connector on the HVAC switch was gone, and the cable wasn't the right length, ended up getting a junkyard unit and all was well.
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the studs are their and the cable is too.. it does not look like it has ever been messed with
i ain't rite
Joined: Mar 2005
Posts: 65,564
Likes: 5,600
From: Marlboro Mental Hospital.
if you can find the part number, do a google search. that is usually how i find my NLA parts.
just looked on evilbay, there are a whole mess for sale. both three lever and 4 lever.
just looked on evilbay, there are a whole mess for sale. both three lever and 4 lever.