A/c Vent Question
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 48
Likes: 0
A/c Vent Question
I have a '96 LT4 and I have a weird question that I hope someone can help me with. When I turn on a/c or heat, the air blows from the defrost and down below no matter what button is pressed. After driving consistently for about 15-30 minutes the air gradually moves to the center vents. If I press a button at that point it goes right back. I was told that if the green light above the vent buttons was flashing there is an error code similar to the ecu. The light is not flashing. I also heard that the vent system is electronically controlled with vacuum.
If nothing else, it would be better if I could make the air blow through the center vents for the summer, a/c works great. How do I fix this?
Please help!
Marco.
If nothing else, it would be better if I could make the air blow through the center vents for the summer, a/c works great. How do I fix this?
Please help!
Marco.
Burning Brakes
Joined: Dec 2001
Posts: 777
Likes: 1
From: Fort Worth Texas
I have a '96 LT4 and I have a weird question that I hope someone can help me with. When I turn on a/c or heat, the air blows from the defrost and down below no matter what button is pressed. After driving consistently for about 15-30 minutes the air gradually moves to the center vents. If I press a button at that point it goes right back. I was told that if the green light above the vent buttons was flashing there is an error code similar to the ecu. The light is not flashing. I also heard that the vent system is electronically controlled with vacuum.
If nothing else, it would be better if I could make the air blow through the center vents for the summer, a/c works great. How do I fix this?
Please help!
Marco.
If nothing else, it would be better if I could make the air blow through the center vents for the summer, a/c works great. How do I fix this?
Please help!
Marco.
If you are lucky it is the plastic check valve that is under the fuel rail cover on the passenger side of the engine. Does your cruise control work? If not replace that black plastic check valve and look at the vacuum lines that plug into the intake.
I have not pulled my controler out yet as it is a pain to get to. Usually it is best to remove the drivers seat(if you are a big or tall person) so you can lay on your back to get to the controler.
Good Luck Hope this helps.
Louis
Racer
Joined: Jun 2006
Posts: 256
Likes: 2
From: San Antonio Tx
i just finished mine today same problem, i replaced the piece located under the fuel rail cover, and cut the rubber part of the nipples 1/2 way off until it was hard plastic with a razor connected it back and all works well, easy job just time consuming make sure you take off the driver seat.hvac box is black with a blue connection on top and is about 4'' by 4'' against the firewall.
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Yeah this is a common problem on alot of GM cars...99% of the time,its the plastic check valve on the vacuum line on the engine somewhere.
Even the L98s havt this problem and the check valve is on back of the engine hooked up to the plastic vacuum tubes.
Other engines,theyre under the cover or on top of the engine somewhere.
THat and the other fixes for the Later C4 cars,such as the LT1 or Lt4,cant go wrong with following that info.
Even the L98s havt this problem and the check valve is on back of the engine hooked up to the plastic vacuum tubes.
Other engines,theyre under the cover or on top of the engine somewhere.
THat and the other fixes for the Later C4 cars,such as the LT1 or Lt4,cant go wrong with following that info.
Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
on the 96, you need to replace the nipples on the box (above the gas pedal). The proper nipples are hard plastic, not soft rubber found in the 96.
I have the correct parts.
pm me if needed.
I have the correct parts.
pm me if needed.
Burning Brakes
Joined: Dec 2001
Posts: 777
Likes: 1
From: Fort Worth Texas
i just finished mine today same problem, i replaced the piece located under the fuel rail cover, and cut the rubber part of the nipples 1/2 way off until it was hard plastic with a razor connected it back and all works well, easy job just time consuming make sure you take off the driver seat.hvac box is black with a blue connection on top and is about 4'' by 4'' against the firewall.Thanks
Louis
Burning Brakes
Joined: Dec 2001
Posts: 777
Likes: 1
From: Fort Worth Texas
Thanks, PM sent with my email address. And any other advise would be a help. I replaced the plastic valve and the vacuum lines under the fuel rail but my AC still blows out the heater ducts.
Louis
Burning Brakes
Joined: Dec 2001
Posts: 777
Likes: 1
From: Fort Worth Texas
Do you still have the parts with hard rubber nipples? I sent you a PM too.
Thanks
Louis
Last edited by Louis Bartay; Jul 24, 2007 at 07:33 PM.
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