AC/Heater controls
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New User
Joined: Dec 2000
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AC/Heater controls
I have a 1986 F250 4x4
Problem: Air flow will not switch from floor to vent to defrost. Stuck in vent position
I checked the vacuum lines and they are Ok. I can hear the door move under the dash.
Is there another door or motor somewhere else?
Any help would be greatly appreciated.
Thank you.
Problem: Air flow will not switch from floor to vent to defrost. Stuck in vent position
I checked the vacuum lines and they are Ok. I can hear the door move under the dash.
Is there another door or motor somewhere else?
Any help would be greatly appreciated.
Thank you.
New User
Joined: Sep 2002
Posts: 1
Likes: 0
AC/Heater controls
I have the same problem with my 1993 ford mustang. Did you ever figure out what the problem was with your truck. Any help would be greatly appreciated.
Thanks
Matt
mslevin4@***.net
I have a 1986 F250 4x4
>
>Problem: Air flow will not switch from floor to vent to
>defrost. Stuck in vent position
>
>I checked the vacuum lines and they are Ok. I can hear the
>door move under the dash.
>Is there another door or motor somewhere else?
>
>Any help would be greatly appreciated.
>
>Thank you.
Thanks
Matt
mslevin4@***.net
I have a 1986 F250 4x4
>
>Problem: Air flow will not switch from floor to vent to
>defrost. Stuck in vent position
>
>I checked the vacuum lines and they are Ok. I can hear the
>door move under the dash.
>Is there another door or motor somewhere else?
>
>Any help would be greatly appreciated.
>
>Thank you.
Posting Guru
Joined: Jun 1999
Posts: 2,007
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From: Oregon
AC/Heater controls
I'm having the same problem with my 85 Bronco. Blows out the vents, but no switch to defrost. I've looked at the flap while running the controls and it will move with the selector; however, not much happens with the final output. Closing the louvers on the vents seem to help. I hate that. The vacuums hoses to the cental distribution point, check valve, and vacuum reservor all look fine.
If the flapper didn't move it would probably be easy to track down, but...
Is vent the default position? There are two hoses running to the flapper actuator. I assume one is for full on, either vent or heat, and the other might be for mixed?. Anyone ever hook up a gauge or just know what these should be doing at the various settings?
If the flapper didn't move it would probably be easy to track down, but...
Is vent the default position? There are two hoses running to the flapper actuator. I assume one is for full on, either vent or heat, and the other might be for mixed?. Anyone ever hook up a gauge or just know what these should be doing at the various settings?
Posting Guru
Joined: Dec 2002
Posts: 1,246
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From: Princeton, MN
AC/Heater controls
The ONLY thing I can add to the mix is that lower vacuum will cause the system to switch from vent to defrost. I know this because one vehicle I drive will only switch over when the engine is revved high (higher rpms = lower vacuum) and two others in the Super Duty forums have had problems involving vacuum loss that caused the airflow to switch itself from vents to defrost even without changing the switch position. I don't really know anything more than that, might be a start?
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