Problem with A/C & Heat 1998 Olds Silhouette

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Old 07-26-06, 05:13 AM
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Problem with A/C & Heat 1998 Olds Silhouette

I'm having a problem with air flowing through the front vents (dashboard or floor) on my 1998 olds Silhouette. The fan is blowing and operates at different speeds, however the airflow seems obstructed. I do notice that when I accelerate and then let off the gas, flow increases somewhat but never to what it should be. It leads me to believe that this is some vacuum issue, but can't be sure. Anyone have a clue? Thanks in advance!!!!
 
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Old 07-26-06, 08:40 AM
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Location: Sterling Heights
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Originally Posted by areyouwireless
I'm having a problem with air flowing through the front vents (dashboard or floor) on my 1998 olds Silhouette. The fan is blowing and operates at different speeds, however the airflow seems obstructed. I do notice that when I accelerate and then let off the gas, flow increases somewhat but never to what it should be. It leads me to believe that this is some vacuum issue, but can't be sure. Anyone have a clue? Thanks in advance!!!!
ayw,
Sounds like you have a vacuum problem that's causing the diverter door not to operate correctly. It could be a number of problems from the door motor itself, to a leak in the vacuum tubing, to a problem with the control unit on the dash.

Another thing to keep in the back of your mind is that even a very small refrigerant leak in the evaporator will emit oil at the leak. This causes the evaporator to become oil soaked and attract dirt; after a few years of this (or sooner) the evaporator will clog and greatly restrict air flow into the cars ductwork.

Have you had to top off the refrigerant on a regular basis? If so, it's entirely possible the leak is in the evap and it has finally clogged to the point of restricting the air flow. Another good reason why topping off is not always a good idea; especially if you donít know where the leak is! ! ! ! ! Replacing evaporators in some vehicles can be a big pain the ass.

I'd look for a vacuum problem first though..........
Phil
 
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Old 07-26-06, 10:31 AM
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Phil,
Thanks! Some air does come through and its cold when the A/C is on, so I tend to think its not a leak. This also happens with the heat - pointing more likely to a vacuum problem (broken hose, etc), but I'm not sure where to start looking under the hood. I have a Hayne's manual, but that doesn't seem to be much help. Any suggestion on where to start - I'll check the door tonight...
 
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Old 07-26-06, 06:00 PM
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The two best ways to find a vacuum leak are with your ears (listen for a hissing sound) and with starting fluid. The latter obviously can be dangerous if you aren't careful where you spray it. If you can't find it by listening for it, then grab a can of starting fluid. Use small sprays around vacuum lines and let it dry/evaporate between shots. If you hit a vacuum leak the engine will rev up. Make sure when you do this that the AC is off so that the engine idle remains constant.

It's still going to be hard to find for two reasons: the type of vehicle (a lot of those vacuum lines are back up under the cowl and hard to access) and you may also have a vacuum leak up under the dash which you can't spray at unless you start taking apart the interior.

Good luck.
 
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