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Don't know never had to do this test. What's the problem with your HVAC?
 

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Discussion Starter #3 (Edited)
The 08 LT of daughters "From cigerette lighter fuse thread" has low or no heat issue. Need to test if blend doors are working or if it is clogged heater core.

I have not checked anything yet just getting the intel to quickly locate the problem.
Found new heater core are cheap enough but seems a PITA for R&R unless you also get a new replacement "shelf/box".
I did read your post on heater core R&R.
If heater core, Is back flush a viable option?
And what is the story of the GM coolant jelling?
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As an update & FYI, Thursday, she claimes she had to replace the orig battery while down in San Antonio. No othe issues reported and has changed oil twice since sept purchase. 8 yr on orig battery?? I would say not bad.
PS she does like the 4 matching OEM hub caps I found for her...she lost 2 of the after market hub caps due to pot holes & oops or whatevers
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Down that line, on my BC, the 08 LS what is the cause of the recirculate blend door clicking? Recalling your suggestion to just deactivate it....
 

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In my case it was the fresh air door and that actuator is in the rear top right corner. You can see it but there's no way to get at it without taking the whole dash apart. So since I never used that button in 6 years of owning the car I just deactivated it by pulling the wire from the connector.
One member on here way back said it was a piece of foam sealant that had come loose and stopping the door from closing completely but I never got to mine to find out the cause of the annoying clicking.
 

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Discussion Starter #5 (Edited)
Just checked the 08 Lt heater.
I do not think the heater core is plugged. Warmed the engine to about 140F as indicated on the Data Information Center.
Both inlet and return lines to the heater core were about 120F (quite warm) while the radiator's lower and upper hose were still cool to the touch.
On the inside, one of the 2 blend door motors( drivers side console side) was not operating. This was the temperature blend door.
I removed & opened the actuator and bent the contacts a bit, just enough to increase their contact pressure, then reassembled.
The actuator now works. After reinstalling, i noticed one of the white blend door levers is not connected also there is no air from dash center registers.
History of this car states the prior owner had purchaced one actuator from RockAuto....both of these actuators appear to habe been removed & replaced before.

Is there an assembly guide or diagram for this area of the HVAC blend doors? From the parts diagram on gmparts 08 chevy cobalt, interior, heater: the white plastic part looks like a lever as shown as item 6

Well Suckcess & failure.

suckcess i found the problem,

Failure in that the shaft to the blend door motor is broken worse, its MIA.....
Poo now for some creative machining.
 

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Discussion Starter #6
Waiting on the JBWeld to setup on the bushing to the remaining shaft on the temp blend door.
I have machined a new shaft to engage the actuator motor and slide into the bushing.
Once the bushing is cured to the blend door, i will mix up another batch and clocking od the blend door to actuator.
Film at 11:00
Wish there was an image of this blend door. And..
How the heck do these blend door shafts break?
 

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Discussion Starter #8
The 1/2" id brass bushing I am using as a coupeling was glued in JBWelded yesterday late.
It should be ready to test later today.
I had to turn one end open a bit to couple to the remainder of the original blend door shaft.

So tonight i plan on gluing the new motor end of the shaft into the bushing after i confirm the blend door operates by hand.
Once i get the temperature blend door into a known position (full cold), i will move the temp to full cold. Then mount the blend door actuators & mounting bracket with fresh JBWeld into the coupling. This should synchronize the control, motor, & door. Then tomorrow afternoom do the final test by pluging in the power to the temp blend door.
@Coby7
It was intresting how to mount the white air diverter cam on the 3 white blend door levers without a diagram.
I used a 1/2" mill to relieve that cam to clear the temperature coupling/bushing.

The Mode Valve Actuator Replacement is a boon...Thank you
On ice buildup. .??? From outside water, say rain, then freeze overnight??
 

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On ice buildup. .??? From outside water, say rain, then freeze overnight??
Just from condensation on the foam seals, people never leave controls midway.
 
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