Intermitent Vent Control Issue
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Cross-Country
Joined: Apr 2013
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From: Hawthorne, NJ
Intermitent Vent Control Issue
Good morning all,
Search has not come up with not exactly what I am looking for. My2002 F250 SD vent control **** seems to be working slowly / intermittently when changing the vents. Regardless of which setting I choose the defrost is always blowing and the floor will not blow at all. I can get windshield only, windshield + Vents but not Vents + floor or Floor only and that is only part of the time. When I switch the selector I can hear the "doors" in the dash move open or closed but sometimes its slow or does not work at all. I have read about the pump in the engine area and the solenoid that actuates the 4x4 system which works. I also have control over the temperature so the bleed door control seems to be fine. And the Fan speed works as well. I am thinking the actual control switch in the array where the vacuum hoses connect may be the culprit bbut thought I would consult you folks here to see if anyone has had this issue. thanks in advance for your time and assistance.
Search has not come up with not exactly what I am looking for. My2002 F250 SD vent control **** seems to be working slowly / intermittently when changing the vents. Regardless of which setting I choose the defrost is always blowing and the floor will not blow at all. I can get windshield only, windshield + Vents but not Vents + floor or Floor only and that is only part of the time. When I switch the selector I can hear the "doors" in the dash move open or closed but sometimes its slow or does not work at all. I have read about the pump in the engine area and the solenoid that actuates the 4x4 system which works. I also have control over the temperature so the bleed door control seems to be fine. And the Fan speed works as well. I am thinking the actual control switch in the array where the vacuum hoses connect may be the culprit bbut thought I would consult you folks here to see if anyone has had this issue. thanks in advance for your time and assistance.
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Joined: Sep 2000
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Likes: 1,678
From: Stephensville WI
You have a vacuum leak somewhere. When there is insufficient vacuum the heating system defaults to defroster mode.
I am not going to say it is the ESOF system. That is a possible area for vacuum leaks, but there are many.
I am not going to say it is the ESOF system. That is a possible area for vacuum leaks, but there are many.
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Cross-Country
Joined: Apr 2013
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From: Hawthorne, NJ
Thank you for your insight... could the leak be the control **** itself? Anyplace I can go to see a schematic of this system components ?
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
Likes: 1,678
From: Stephensville WI
The leak could be anywhere. Your truck is over 20 years old. Rubber deteriorates. Seals crumble. Don't get fixated on one part or system.
My method of finding a vacuum leak scares some people, but it works for me.
Start your engine. Take a propane torch, open the valve but don't light it. Pass the torch opening over every hose, valve, fitting and gasket mating surface. If you hear a change in the idle you have probably found your leak.
Some also use carb cleaner for the same purpose.
My method of finding a vacuum leak scares some people, but it works for me.
Start your engine. Take a propane torch, open the valve but don't light it. Pass the torch opening over every hose, valve, fitting and gasket mating surface. If you hear a change in the idle you have probably found your leak.
Some also use carb cleaner for the same purpose.
Thread Starter
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Cross-Country
Joined: Apr 2013
Posts: 56
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From: Hawthorne, NJ
The leak could be anywhere. Your truck is over 20 years old. Rubber deteriorates. Seals crumble. Don't get fixated on one part or system.
My method of finding a vacuum leak scares some people, but it works for me.
Start your engine. Take a propane torch, open the valve but don't light it. Pass the torch opening over every hose, valve, fitting and gasket mating surface. If you hear a change in the idle you have probably found your leak.
Some also use carb cleaner for the same purpose.
My method of finding a vacuum leak scares some people, but it works for me.
Start your engine. Take a propane torch, open the valve but don't light it. Pass the torch opening over every hose, valve, fitting and gasket mating surface. If you hear a change in the idle you have probably found your leak.
Some also use carb cleaner for the same purpose.
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
Likes: 1,678
From: Stephensville WI
A Power Stroke will have a vacuum pump. That considerably changes the troubleshooting methods used.
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Cross-Country
Joined: Apr 2013
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From: Hawthorne, NJ
Well that makes more sense... so there is no vacuum pump on a Gas powered power stroke?? Have to buy a new propane tank then...
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Hotshot
Joined: Jan 2004
Posts: 19,760
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From: St Louis
so there is no vacuum pump on a Gas powered power stroke??
This does not sound like a supply vacuum leak issue. If it was, ALL outlet airflow would default to the defrost ONLY. <<-- THIS IS A CRITICAL OBSERVATION! Most likely, it's an issue with with the one specific vacuum-operated mode door that is malfunctioning.
Sounds like it's an issue with the panel-floor door is stuck in the "panel" position which blocks off most airflow to the floor outlets. This could be due to a fault in the vacuum portion of the mode switch, an open vacuum line, a failed vacuum motor or its linkage, or a damaged/jammed door inside the plenum.
Look for the vacuum motor with the blue and yellow vacuum lines. IIRC, it's behind the glove box on the SD trucks. Make sure that they're both connected and the linkage to the mode door bell crank is intact. Switch the mode to FLOOR and see if both lines have vacuum (vacuum supply enabled, of course). If vacuum is lost to both, that mode door motor defaults to the panel and defrost outlets only.
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FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
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From: Stephensville WI
I never say never. Once you start looking at the chassis cab rigs you never really know what you'll see.
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From: Hawthorne, NJ
There's no such thing as a "Gas powered power stroke". "Power Stroke" was the marketing name for the diesel power plant. A separate vacuum pump is required for diesels (as well as the newer Eco-boost engines).
This does not sound like a supply vacuum leak issue. If it was, ALL outlet airflow would default to the defrost ONLY. <<-- THIS IS A CRITICAL OBSERVATION! Most likely, it's an issue with with the one specific vacuum-operated mode door that is malfunctioning.
Sounds like it's an issue with the panel-floor door is stuck in the "panel" position which blocks off most airflow to the floor outlets. This could be due to a fault in the vacuum portion of the mode switch, an open vacuum line, a failed vacuum motor or its linkage, or a damaged/jammed door inside the plenum.
Look for the vacuum motor with the blue and yellow vacuum lines. IIRC, it's behind the glove box on the SD trucks. Make sure that they're both connected and the linkage to the mode door bell crank is intact. Switch the mode to FLOOR and see if both lines have vacuum (vacuum supply enabled, of course). If vacuum is lost to both, that mode door motor defaults to the panel and defrost outlets only.
This does not sound like a supply vacuum leak issue. If it was, ALL outlet airflow would default to the defrost ONLY. <<-- THIS IS A CRITICAL OBSERVATION! Most likely, it's an issue with with the one specific vacuum-operated mode door that is malfunctioning.
Sounds like it's an issue with the panel-floor door is stuck in the "panel" position which blocks off most airflow to the floor outlets. This could be due to a fault in the vacuum portion of the mode switch, an open vacuum line, a failed vacuum motor or its linkage, or a damaged/jammed door inside the plenum.
Look for the vacuum motor with the blue and yellow vacuum lines. IIRC, it's behind the glove box on the SD trucks. Make sure that they're both connected and the linkage to the mode door bell crank is intact. Switch the mode to FLOOR and see if both lines have vacuum (vacuum supply enabled, of course). If vacuum is lost to both, that mode door motor defaults to the panel and defrost outlets only.
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
Leave the radio alone.
Empty out the glove box (or just dump everything on the floor when you drop the door all the way open). Squeeze the ends to allow full motion and flip the door down to access area behind there.
Empty out the glove box (or just dump everything on the floor when you drop the door all the way open). Squeeze the ends to allow full motion and flip the door down to access area behind there.
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Cross-Country
Joined: Apr 2013
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From: Hawthorne, NJ
Ok thank you for the suggestion... however I have to install the reverse camera and might do it while looking to fix this.. but I will try without taking the radio out just to get the experiance.
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