HVAC diverter knob does nothing.. [Archive] - GrandAmGT.com Forum

PDA

View Full Version : HVAC diverter knob does nothing..


ENDEE666
08-15-2011, 08:23 PM
When I have the A/C on, everything else works except the diverter control. Temp works, fan speeds work. But no matter what I do with the 3rd knob, the air still comes out the face vents (seems slightly at the top dash ones too).. Is this an issue within the HVAC unit or is the problem a relay or something elsewhere? Not a big problem now, but if I need to defrost in winter or warm my feet, it will be an issue then..

AaronGTR
08-15-2011, 08:44 PM
All that is vacuum controlled. If you pull off the trim piece and unbolt the HVAC control unit and pull it out, you'll see a bunch of vacuum lines running to the back of the dial. Which position you turn the dial too controls which lines have vacuum applied and controls the air flow to the vents, the heater core, and the A/C evaporator.

If there is a vacuum leak in one of those lines, the controls won't work properly, or at all. Check the lines and connections for cracks or signs that they are getting dry and old. The main vacuum supply line is a gray plastic tube that runs through the wire harness into the engine bay and connects to the upper intake manifold next to the fuel pressure regulator. Make sure that line is connected and isn't cracked or split. It sees a lot of heat and can get damaged once it gets old.

AleroB888
08-15-2011, 09:06 PM
The main vacuum supply line is a gray plastic tube that runs through the wire harness into the engine bay and connects to the upper intake manifold next to the fuel pressure regulator. Make sure that line is connected and isn't cracked or split. It sees a lot of heat and can get damaged once it gets old.

Do you know where that gray supply line feeds thru the firewall in the dash area? I need to find that, too.

ENDEE666
08-15-2011, 09:09 PM
Yeah a pic of that & where on the intake mani it connects would be awesome. Only had this car a few weeks.

HOYS
08-16-2011, 12:08 AM
Do you know where that gray supply line feeds thru the firewall in the dash area? I need to find that, too.

It is in the harness clump for EGR, EVAP, MAF, TPS, IAC and the likes.

AaronGTR
08-16-2011, 02:51 PM
I already said it connects to the intake manifold next to the fuel pressure regulator. It's on the front right corner, has a 90 degree boot on it, and a gray tube coming out of it that goes into the main wiring harness. You can't miss it. If you can, then you shouldn't be working on cars.

Once it goes into the main harness, it's wrapped up with all the wires and goes through one of the big rubber grommets in the fire wall (upper one I believe it is?), then it goes up under the dash and comes back out of the harness somewhere behind the dash. It's not easy to see. If you really really wanted to trace all of it, you're going to have to remove a lot of interior trim and a few parts inside the engine bay, and unwrap a LOT of wire loom.

ENDEE666
08-17-2011, 08:02 PM
My vac nipple on that part of the intake mani looks different than you describe, and different from what a user on GA Owners Club forums posted...

This is the pic given to me, NOT my car-
http://www.gaownersclub.com/forum/showpost.php?p=1846763&postcount=5

And THIS IS my car below, I put colored dots to follow which vac line goes to the check valve & which goes to the "T"-
http://i1207.photobucket.com/albums/bb478/endee666/IMG00366-20110816-1342.jpg

ENDEE666
08-17-2011, 08:04 PM
As you can see, very different. I have only had this car a few weeks. I did replace a few vac lines because they were broken/deteriorated. But I did not change anything about where they went to/from. This is how I got the car.

cutlsp
08-17-2011, 08:42 PM
Your car has California emissions controls on it that's why it looks different. Hopefully you can find a member on a forum somewhere with a California equipped car that has the vacuum lines intact.

ENDEE666
08-17-2011, 08:48 PM
It does? That would be surprising, I am the 2nd owner and the car has always been a NY car. I don't need CA emissions, if there is a way I can put it to non-CA status and fix this..

HOYS
08-17-2011, 09:44 PM
It does? That would be surprising, I am the 2nd owner and the car has always been a NY car. I don't need CA emissions, if there is a way I can put it to non-CA status and fix this..

The term "CA" emissions is just because CA is the strictest about them. Many eastern states have the two EGR setup as well.

ENDEE666
08-17-2011, 10:44 PM
OK, I re-ran some of the vac lines in accordance with the diagram on the pass strut tower, shown below. A few were indeed wrong. Now everything is exactly how this diagram says it should be, but I still get no changes when moving my HVAC diverter knob.... :(

Diagram:
http://i1207.photobucket.com/albums/bb478/endee666/VacDiagram.jpg

AaronGTR
08-18-2011, 03:08 PM
Yeah, you have the CA/NY emissions with the air pump for the exhaust manifold. I've never seen one of those close up so I'm not sure what the difference is, but there has to be a connection there somewhere for the HVAC controls. Need to find that little gray tube.

ENDEE666
08-18-2011, 03:58 PM
FIXED!!!! Thanks to Rix on GA Owners!! I managed to find the old vac line in the harness bundle, ran it to a tee as he said and all good now! Thanks so much for the help everyone!!