Switch on dash won't change direction of air to vent, etc.
I have a 1999 F-150, 4.2L, V-6. The switch on the dashboard that controls the air direction to the vent, floor, defrost, etc. sends all the air all the time to the defrost. The other switches work fine. Can you help me?
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Re: switch on dash won't change direction of air to vent,...
You have a vacuum leak,defrost is the default postion,no vacuum to controls. Check the small black vacuum line that goes thru the firewall on the passenger side of the firewall and trace it back to see if you can locate a leak. It will go to a vacuum resivior then to the intake manifold.
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Im sure you know there is a selector switch for foot, dash & defrost modes for heat or air. It could be either a fuse for damper control or linkage motor for damper control is gone bad. Hope this helps
I just fixed mine. The lever that opens and closes a door that directs the air flow to the defroster was broken. To be more specific, the plastic lever the actuator attaches to was broken. The actuator and the vacuum system were operating properly. It is simple to see but hard to get to. Remove the glove box and look up and to the left for a silver vacuum controlled actuator. I was able to fabricate another lever and attach it to what was left of the OEM lever.
If you cannot change the air flow from the heater vents, defroster vents, to dash vents, etc. as your control switch indicates the problem could be a loose vacuum line. It could have come loose from the engine under the hood. If not you will need to remove the control from the dash and check for vacuum at the control. If you have vacuum there you will need to replace the switch,
This is a common problem on all Astro/Safari vans. The problem is a leak in the vaccum lines that control the vaccum switch responsible for changing air direction from the defrosters, dash vents, floor vents..etc. Many of the problems that plaque the Astro/Sarfari vans and many other "Mini-Vans" is the build up of excess heat in the engine compartment. It\'s a tight place to put a V6-4.3 Vortec engine and the heat generated bounces back and cooks everything on the engine (coils, modules, sensors, wiring, and of course plastic vaccum hoses). No need to mess with your switches or anything behind the dash -- replace those thin plastic vaccum hoses to operate the vaccum switch (located just below the A/C canisters, to the right of the heater/ac blower housing) and your dash switches will magically send heated or cooled air where you want it.
I would say that the control unit isnt switching properly,from the mode button moving the vents air flow direction,best bet is to try and swap a mates one and see if the mode changes the airflow to the main vents,it may be the unit isnt allowing the switching,i think theyre vacuum controlled
u have a loss of vacuum to the ac mode control switch, this switch applies vacuum to diff vacuum motors to move air to diff outlets, dash, floor, defrost etc. either the vacuum line or vacuum resivior at the engine is leaking or the mode control is leaking vacuum.
Defrost is the default mode so if the system fais, you alays have defrost. The mode doors are controlled by vacuum motors. I would suspect a vacuum leak in the engine compartment on the hose going from the engine through the firewall and into the heater controls. Some systems have a vacuum storage canister that can also leak. The canister stores vacuum when vacuum drops going up a hill.
Or, you have a bad heater control head that is not passing vacuum to the vacuum motors on the mode doors.