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How hard does the HVAC fan blow the air in your car? Mine is like a whiff from the driver side vent and a slight bit more from the center and passenger vents. It could not keep me warm driving home with the roof off last night. This car is new to me so I'm not sure how wimpy the HVAC system is in the Vettte. 97 M6 coupe with dual zone. I've always been driving with roof off up till now so never noticed how weak the flow was.
Posts: 6 | From: Ontario, Canada | Registered: May 2008
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Is the air also coming out of the defroster and floor vents at the same time? If so, look for a leak or broken vacuum line underneath the battery (which could have leaked in the past) or behind the intake manifold.
Posts: 4601 | From: Long Island, NY | Registered: Nov 2000
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My Silverado had low airflow and somebody suggested checking the filters under the dash. I didn't even know that it had any of those, but that is what it was. I would guess the Vette has some, too.
Posts: 832 | From: arizona | Registered: Nov 2001
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The C6 has a cabin air filter behind the battery, but I don't think the C5 has one. The air inlet for the HVAC system is on the cowl under the rear edge of the hood by the drivers side wiper arm, it's rather large but you should check it out also.
Posts: 1623 | From: North Augusta, SC | Registered: Apr 2003
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I don't have a manual for a car that old, but I'd check about the filters before spending alot of time diagnosing the rest of the system. My filters were almost completely blocked. I could've wasted alot of time and money trying to fix something that wasn't broken. My truck is a '99.
Posts: 832 | From: arizona | Registered: Nov 2001
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OK I've finally had a chance to look into this problem a bit more. When I run the unit in manual and hit the mode botton to switch from dash vents to defrost to feet, there is no difference. The air flow is just a whiff out of all vents at the same time. The mode changes on the display but I'm pretty sure the diverters aren't moving. If I run the unit with the engine off, I can't here any movement when I switch modes.
Correct me if I'm wrong, but I picture the system as being a selection of flaps or doors that open and close to adjust were the air flows. Something must power these doors and I'm going to assume it's engine vaccuum from Bruce's earlier reply. He says I need to disconnect the battery and look underneith for a broken vaccum line.
I have some questions that maybe you guys could answer. 1) Am I correct in my thinking about how the system works? 2) Am I looking in the right direction? 3) I have checked for error codes for the HVAC system and it show none. Why would this problem not register a code? 4) Wouldn't the engine run poorly or throw a code if I had a vaccuum leak?
I'd really appreciate some opinions, Thanks. Posts: 6 | From: Ontario, Canada | Registered: May 2008
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Yes. It's run by vacuum. And it is separate from the engine vacuum. Often a battery leak will drip down onto the line or it becomes unhooked from the back of the manifold. If you can get under the car, it may be easier to see the canister and connections under the battery.
Posts: 4601 | From: Long Island, NY | Registered: Nov 2000
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Pulled the battery last night. It was leaking; don't know why. There was no crack in the case; it seemed to be just leaking out the caps on top. It's only 2 months old, so I'll be taking it back tonight.
Vacuum line was broken; not sure if it was due to battery acid or rubbing or fatigue.
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Make sure you neutralize all of the leaking acid using baking soda/water mixture. And check to see if it leaked on the PCM and TAC modules and their wiring.
Be sure not to over torque the battery posts as this is a frequent source of leaks.
Posts: 4601 | From: Long Island, NY | Registered: Nov 2000
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