so last night i went to turn my defroster on because my rear window was foggy so was the front. i switched the left side control to the windshield logo (all the way to the right) and it didnt switch over. air continued to blow out the 4 vents. i was like uhh....
so i put the setting back to the top vent and they worked fine. i switched the climate control to heat and the heat worked.
switched it back to AC and pressed the ac button and the recirculate button which makes it more colder and that worked too.

no other settings like feet and windshield worked.

what do i do..? im out of warranty bc i have 47,000 miles on the car.

 

I don't have an 08 instead I have an 06 and my manuals are for the 06. Though I would imagine that not much has changed for the HVAC system in 2 years.
So I looked up your problem in my 06 manuals..

Here is what it says.

1. Turn on engine, select defrost, select maximum blower: Does sufficient air flow from the defroster outlets? You indicated NO: Go to 11: "Go to Air delivery improper"
2. Now under Air Delivery Improper: Turn engine ON with Blower OFF: Is the blower off? You indicated YES
3. Place blower motor control in each speed postion: Does blower motor operatate: You indicated YES
4. Does the blower motor operate correctly for each speed position? You indicated YES (You didnt mention that it did not since its not what you were asking about)
5. Is the HVAC control assembly inoperative in all positions? You indicated NO You mentioned that it worked in a few of them
6. Test the ignition 1 voltage circuit of the HVAC controller for an open, for a high resistance or for a short to ground.
7. Inspect for bad connections at the harness connector o the mode actuator.
8. Inspect the mode door and any attaching linkage for any binding
9. Inspect the ductwork for any debris that would prevent airflow through the duct work.
10. Inspect for bad connections at the harness connector of the HVAC control assembly.
11. Replace the mode actuator.
12. Replace the HVAC control assembly

Hope that helps you.
If not I've got more, but I didn't want to type too much inhere and overload you. Alot of it is if yes go to suchandsuch step if no go to next step.

 

how would i replace the mode actuator? beause no matter what setting i have it on with the fan speed at 1 2 3 or 4 it just blows air out of the front vents.
nothing for feet or feet and defrost or anything.

i made an appt at chevy to have em look at it but im not under warranty so i dont know how much this would cost me

 

I've never done that job before, but here are the steps in the 2006 manual for replaceing it. The pictures arn't really all that great though, but it looks like your having to pull off the panel to the right of your right foot as you sit in the driver's seat. To replace the mode actuator it tells you to remove the Air Temp actuator. I don't know what it would cost at a dealership. You can probably get a quote or estimate from Sarah or just call your local dealership and ask. Yes I know you're 2008, however I only have the service manuals for the 2006.

1. Remove the fuse labeled HVAC CTRL (BATT)
2. Remove the steering column filler panel.
3. Disconnect the air temperature actuator electrical connector.
4. Remove the air temperature actuator screws.
5. Remove the air temperature actuator.
6. Disconnect the mode actuator electrical connector.
7. Remove the mode actuator assembly screws.
8. Remove the mode actuator assembly.
9. Important: The Key should be in the OFF position when connecting the electrical connectors toensure proper calibration
10. Install the mode actuator assembly
11. Install the mode actuator assembly screws
12. Tighten the screws to 2.2 N m or 19 Inch lbs
13. Install the mode actuator electrical connector.
14. Install the air temperature actuator.
15. Install the air temperature actuator screws.
16. Tighten the screws to 2.2 N m or 19 inch lbs
17. Install the air temperature actuator electrical connector
18. Install the steering colum filler panel
19. Install the fuse labeled HVAC CTRL (BATT)
20. Important: Do not adjust any controls on the HVAC control assembly while the HVAC control assembly and actuators are calibrating. If interrupted improper HVAC performance will result.
21. Start the engine and let run for one minute.

 

I've had a good portion of my hvac system apart to try fixing a similar problem.
If you follow insylem's instructions, steps 3-8 all refer to the control motors that adjust the temperature and which vents the air comes out of. They look identical in shape and size, but one is screwed to the flap that controls the temperature, and the other is screwed to the mechanism that adjusts the air flow. If I remember correctly, the one you are looking for is mounted higher and closer to the back of the radio. Check to make sure that the electrical connector is still plugged into it. If it is, go ahead and remove the actuator (should be three small screws, I think they are 7 or 8 mm.) Once you have it removed, plug the connector back into it and see if it turns when you turn the dial on the hvac control. (You'll have to put the fuse back in to do this) There is a square hole on it that will turn when it is working. If it doesn't turn, then replace it. If it does turn, then reach up and try turning the white plastic piece that it connects to. This white plastic piece directly opens and closes the flaps that control where the air comes out of. If that piece does not turn like it should, then you are in the same boat as I am.... Something is messed up inside. Some day I'll have to tear into a wrecked Cobalt in the salvage yard and remove the whole hvac system.

 

ah i dont have the time to messs with all of this. to the dealer its going

 

Good Luck
Let us know what they did to fix it please.

 

yeah im kinda wondering what there guna charge me

 

Cobalt08LS,
Have you gotten this looked into since your last post? Hope all has gone well!
Sarah, GM Customer Service

 

Get a new HVAC board from a scrap yard...$10 fix.

Or it might be the contacts need cleaning. The grease on them holds on to dirt VERY well. Have you ever opened it before?

 

Ever get it fixed?

 

Yes he got it fixed. He ended up accidentally somehow bending the actuator that switches between top and bottom vents when cutting out the back part of the radio bay.

 

yes i forgot to post. but i got it fixed. bent/broke something when installing my double din radio. didnt even know.
$100 out the door fixed took 45 mins