Ac Bogging Down Truck

[Arty]

I have an issue with my 09 3500HD w the 6.0L and was wondering if anyone has experienced this issue and knows of a fix. Prior to this week using the A/C didn't cause any noticable engine decrease. Now using the A/C causes the engine to bog down. It has a hard time on a level surface going 65 w/o downshifting. I checked for hot air sucking in the intake (another reason for it to have crappy performance) but it is all clear from the fender. Could this clutch gap issue cause an engine to bog down?

 

I also notice that when I start it up in the morning, she takes a while to get going. Very slow and unresponsive throttle. Once up to operating temp, then fine. Only got 15K...

 

Thank you

[bill190]

The way this should work is when the A/C is turned on, the engine computer is "notified" and it increases the engine power via the IAC valve. And same thing with other loads on the engine like headlights turned on or other electrical loads. Adds a bit of power to the engine.

 

So something with that system might not be working right.

 

If it is under warranty, take it to the dealer.

 

If not, start by checking the electrical connectors under the hood, especially to the IAC valve.

 

Then look in your owner's manual for the location of all "fuse boxes" and check all fuses. How to test fuses...

http://www.dinosaurelectronics.com/Test_Fuse.htm

 

If that does not find the problem, remove the IAC valve and look inside where the pintle moves in/out. Be sure there is not any crud there preventing it from moving freely. Look at the air openings in the back and be sure they are not clogged. That air can flow. DO NOT TURN ON THE IGNITION WITH THE IAC VALVE REMOVED! The pintle will go shooting off into the boonies!

 

If that does not work, a lot of this stuff is computer controlled. So reboot! That is remove a battery cable for about 10 minutes, then reinstall. Then turn on the ignition and don't touch any buttons for 1 minute. (Some things "resynchronize" when power first restored.) Then start the engine.

 

Other than that, you would need a GM factory service manual set to troubleshoot the problem. Or take it to a GM dealer.