Weather there are charging or regulation issues that need addressing. Both will ultimately lead to the removal of the alternator for testing and/or replacement. On the Cobalt this is a slightly more involved task due to the location of parts, but not a very difficult task to be done in the driveway. There is no need to pay a shop hundreds for what can be done in an afternoon with the proper tools.
I start by removing the bug plastic shroud, first cleaning around the oil cap so i don't dump all of the dirt into the engine when i remove it, then with the cap removed the two fittings are unsnapped and the whole unit is lifted off. Next the airbox is first blown out to remove dirt and dust by the throttle body before loosening the hose clamps and the small hose from the engine. One plastic retainer clip is also lifted out as well. The whole unit is lifted off before stuffing clean paper towel into the throttle body and the air box opening.
I take some time to blow out all of the garbage I find under here, a lot of the cable loom is destroyed, so i've replaced it and re-taped the harnesses with super 88 3m. An inspection of the air filter showed that I might as well order one too.
Next will be the belt, accessed from under the car from the passenger side, using a jack and stand, just high enough to clear the tyre for removal. With the tyre removed the wheel is turned to the right for more access to work. I remove the locking clops and 7mm screws from the access panel as shown to deflect it for exposure to the engine. I removed 5 clips and two screws in total.
The lend tool at autozone OEM 27115 is too big to do the job. The cheapest way to do this is two parts off of amazon, gearwrench 368072, which is the wrench, and the 3/8 adapter for that wrench.
part 338071 also provides for an extension to make this easier .
GEARWRENCH Replacement Ratcheting Wrench for Serpentine Belt Tool Set 3680D - 368072 - - Amazon.com
The 3/8 adapter
Shown highlighted where the 3/8 fitting is , we see how the tool goes in and rotated counter clockwise to loosen the belt. and pull it off of the pulley. After removing the tool, I then with the belt loosened removed it from the alternator pulley. The cables are not easy to remove from the alternator until its unmounted so I remove the three 13mm bolts. The connector can then be removed and then the nut holding the second cable. With the the water hose is bent slightly out of the way and the alternator negotiated out of the car and inside to the bench.
For assembly: The alternator is negotiated back into position so that the cable can be reconnected onto the stud. Then aligning it to mount back onto the car with the three bolts. These are tightened to about 16lb/ft The belt is then brought back around the alternator which brings the project back to belt installation. The tool is reused to rotate the tensioner so that the belt can be brought around the pulley.
Now replacing the air filter with an A2956C from AC delco, I replace only what is need to get the car running, this includes the manifold airbox and filter. The battery is then reconnected and the car started for evaluation. I see that the overall voltage is reduced, so I continue with the addition of the service cover re-installation, tyre , 100ft/lbs and rim, and then the engine cover, lowering the car to completion.