rough idle with a/c on?

[mikep453]

my wife's 2001 GMC Yukon idles smooth with the a/c off but when you turn it on it begins to idle rough. it doesn't die but it just rough at idle. it doesn't stumble when your driving either. any suggestions on where to start. I am going to replace the fuel filter because it needs to be changed anyway but any other suggestions?

[Shane77624]

Sounds like it isn't compensating for the increased load and is pulling the idle too low. What are your RPMs at idle without the AC and then with the AC?

[bigjohntex]

How many miles are on the spark plugs. I have seen issues with them that would cause a rough idle under a load (a/c on).

[Coacher]

I always cut my A/C off when idling...I was told it will make the compressor last a lot longer.

[mikep453]

the spark plugs don't have more than 10,000 miles on them and its not so much when idling parked but more so when you stop at a stop light. I think something is wrong with the compressor because just this evening the compressor started making a loud strange noise. a friend of mine told me that the compressors have an internal belt that messes up on them pretty often and it will cause a loud noise similar to what mines doing. however, i'm not sure if that is connected to the rough idle or if two things just went wrong at once, lol.

[Shiner]

try cleaning the throttle body. but dont do it abrasivly. soft rag, soft toothbrush, with a brake cleaner or they make a throttle body cleaner. we fix a lot of idle issues like this. Hold throttle plate open and clean. should be done with every tune up if not before

[tx07]

Look at the aircompressor when the truck a running with ac is on.
If the compressor is kicking in and out that's why you feel ruff engine.
Sparkplugs or wires or the fuel pressure regulator cause this under load also.

[WoJo]

Vacuum leak??

[Extremebowman]

I had a '99 that did the same thing, I can't remember what caused it though For some reason it seemed like it was a vacuum leak like WoJo said, but I don't recall?