ac/heat issues...
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Freshman User
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ac/heat issues...
The door that controls the dash/defrost moves to defrost with higher rmps. i am pretty sure its a vacuum leak somewhere. but what i dont know is what line controls that and where that door is exactly or what to look for. any help would be appreciated. thanks
Cargo Master
Joined: Jul 2009
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From: Des Moines
It's possible it's a vac leak on the supply line to the heat/AC controls. Get under the hood. Depending on the year of your truck, the supply line should enter the firewall on the passenger side of the engine bay. Regardless it should be black in color and very small. If you have a vac gauge hook it up and test it. If not.... well, what I would do is suck on it and see if holds. But that's what I would do....
Fleet Owner
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From: Kentucky
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Freshman User
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it was broke but now i fixed it, and i believe that is for the blend door, or either the vent door, i dont know if those two are the same or not.
Fleet Owner
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From: Easton,Ks
The Blend door is cable controlled, not vacuum.
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ok so im lost then, when i switch it from the selector it switches fine, but when i accelerate (if its on vent) it swaps to the dash, i dont know if it does it while its on the floor. i did notice that the black vac line that hooks into that coffee can looking thing on the pass side is broke, i dont see how that would have anything to do with the selector door. i forgot to add 89 f150 2wd 5.0.
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Fleet Owner
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From: Easton,Ks
The coffee can has nothing to do with the Heater-A/C vacuum system, that can is for emissions only.
But if bad it still needs to be fixed.
But if bad it still needs to be fixed.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
ok so im lost then, when i switch it from the selector it switches fine, but when i accelerate (if its on vent) it swaps to the dash, i dont know if it does it while its on the floor. i did notice that the black vac line that hooks into that coffee can looking thing on the pass side is broke, i dont see how that would have anything to do with the selector door. i forgot to add 89 f150 2wd 5.0.
The engine vacuum goes down when you accelerate and the vent vacuum tank and check valve should hold the vacuum long enough until you go back to normal driving.
You could have a bad vacuum hose in this system, check valve or bad selector switch.
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Freshman User
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When it switches when you accelerate it means you have a vacuum leak from the engine vacuum tree to the dash vacuum system. The vent vacuum tank is on the side of the A/C box under the hood.
The engine vacuum goes down when you accelerate and the vent vacuum tank and check valve should hold the vacuum long enough until you go back to normal driving.
You could have a bad vacuum hose in this system, check valve or bad selector switch.
The engine vacuum goes down when you accelerate and the vent vacuum tank and check valve should hold the vacuum long enough until you go back to normal driving.
You could have a bad vacuum hose in this system, check valve or bad selector switch.
Fleet Owner
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From: Easton,Ks
No it will not fix the Vent problem as that is part of another vacuum system. The system with the big coffee can is for the EGR, TAB & TAD (A.I.R.) control and is the system that the under hood diagram is for. If you are saying you have a vacuum leak in that system yes you need to fix it so that system will function.
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