97 Pontiac Grand PrixSE-No Ventilation Control

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  #1  
Old 06-27-03, 06:35 AM
dishguy
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97 Pontiac Grand PrixSE-No Ventilation Control

The interior ventilation system seems to be "stuck" on the Bi-level mode. Air is coming thru the upper and lower air passages/vents and maybe a tiny bit from the defrost vents but changing the selector makes no difference.
This makes the A/C not too effective right now nor would the heating be very good at the floor level since one cannot direct the air flow where desired.

On the airflow selector knob, at the most CCW setting (which is AC Max), a tiny green indicator comes on which I think is also the AC on indicator. Since this works, I'm guessing it may not be the selector switch itself.
I know very little about how this is supposed to work but assume the control directs 12volts to various solenoids/motors, etc to move appropriate "vanes" or "valves" in the ductwork to direct the airflow as selected. (Anyone know how many of these are involved in this car?)
Anyone have any experience with this type problem? The former owner says it was always like this when he owned it and did nothing about it. I'm hoping that it is not some deeply buried actuator/s that have gone bad or are stuck and so making it a bearcat to get to. Rather hoping that a common power lead is loose or such since NONE of the settings result in any change of air movement. I have looked thru fuses and find none bad that would seem to be involved in this function.
I am an electronics tech so am familiar at least with troubleshooting and looking for supply voltages being present where they should be, etc.
Thanks for any help!
 
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  #2  
Old 06-27-03, 06:49 AM
Joe_F
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A wiring diagram is likely needed here. Get that and you should be in good shape. Check autolibrary below or alldata.com
 
  #3  
Old 06-27-03, 08:05 PM
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Best memory tells me your car operated the various positions by vaccum, not electrical..But I could be wrong, again, today..
Does the other controls work properly? Meaning you can change from max a/c to "normal" a/c to vent, to heat?
If you take a peek up under the dash (usually from the passanger side) you should be able to see a vaccum harness with multi colored vaccum lines.. You can trace these to the different door acuators to see which ones (actuators) move freely ect..
The main thing I'm heading towards is a vaccum line knocked off, a vaccum line broken or a bad switch.. Typically, if vaccum is lost on the supply line, the air blows out the defrost vents, and no where else, so am mentally eliminating that for now...
 
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Old 06-29-03, 10:03 AM
dishguy
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Thumbs up

FIXED !!!
Thanks for the super tips, "msargent" . Actually I have a temporary fix until I can get the part/s. I was able to get some thoughts and info from my nephew (a mechanic) which, along with your thoughts, msargent, led me to the problem area.

I had been told by the local Pont dealer that this was an electrically operated system on this car..... not... at least the majority is vacuum controlled as you suggested, msargent.

I finally discovered a (the) vacuum line off top of engine and traced it to where it went down under the windshied washer fluid tank. Had to remove the metal brace and the tank to see where the vac line went. There next to the battery I discovered another end of a vac line that had broken off a sort of "T" juction. One line was from the engine, another went into a bundle which went thru the firewall into car's interior and this third one (after more effort to trace where it went) went clear across the car to the drivers side under the fender to a round plastic "resivoir" (sp?)
for the vacuum! Wasn't sure it would work but just for the time being I connected the main line directly to the one entering firewall and wal-la, the controls now work! What a great feeling to have the air directed as selected and now the AC is forcefull out of top vents and other positions shift air flow as it should be.
Only thing was in this case that all the airflow either "defaulted" to the sorta bi-level position or else when the line was broken, that is where it had last been set.
Just need to get that "T" plastic piece and should be completed.
Thanks again for the suggestions.... so glad it didn't involve a lot of tearing into the under/behind dash as that would take a great deal of time and be a lot of work.
Best regards :-)
 
  #5  
Old 06-29-03, 11:06 AM
Joe_F
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Good for you .

Like the dealer, I assumed it was electronic (as many are of this era.) Would have helped if you had said that it was not
 
  #6  
Old 06-29-03, 11:45 AM
dishguy
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Joe,
Thanks for your effort to assist. If I had known on my first post that this was vac controlled, I would have said so..... obviously from what I stated, I had the impression and or had been informed that it was all electric/electronic or I wouldn't have worded my discussion that way.

One of my first stops was to the local GM dealer for the most accurate, informed data. Their service mgnr is the one who "scanned" thru his on-line info and gave me that mis-information. I don't know if he was able to get the precise info but I left there thinking it was electricly operated. If the dealership doesn't have access to the best possible data or fails to relay what he knows to me then it is hard to know what to put stock in.
I certainly don't expect all the voluteers that "work" this board to be super experts at every make, model variation and detail but with their variety of experience and knowledge it was my hope that perchance someone might have had a recent enough encounter with one like this or have another source to confirm/dispute what info I had been given. That is my whole point in looking at more than one source for assistance....

Again... no offense intended and I truly appreciate your help
 
  #7  
Old 06-29-03, 08:15 PM
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Glad that you got it fixed!! Thats the main thing!! Good job!
 
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