Truck idles rough when A/C is turned on, just replaced all the spark plugs about 4000 miles ago. Problem just started in the past 3-4 days. If you turn the A/C off it seems to idle normal. There are no check engine lights on and everything else seems to work fine. Its the start of football season and I need to drive my son to many out of town games and I don't want something major to break on us. Please help!
The idle air control valve (IAC) should increase the idle speed when the AC is turned on to compensate for the additional load on the engine. Is that happening?
July, 30, 2013 AT 9:08 PM
It doesn't seem to be, when the A/C is on and the rough idle starts it seems like the RPM goes down and struggles to catch back up
July, 31, 2013 AT 3:38 PM
Remove the IAC and have a helper turn the key on and off. There is a pintel valve that is on the end of the IAC. It should move.
Let me know.
August, 1, 2013 AT 3:28 PM
I heard only the 4.7 liter rams had the IAC not the 5.7 liter which my truck is. Is this true? Also could a bearing in the A/C compressor be going bad causing more drag on the engine since it only idles rough when the A/C is turned on? Someone mentioned a vacuum leak but I figure that would cause a problem with the A/C running or not. So now I am lost
August, 1, 2013 AT 8:44 PM
That is correct. The 5.7 doesn't have one. As far as the compressor going bad, that is possible. However, I would think you would hear a noise from it. Check for vacuum leaks to see if there are any. You may just notice the rough idle more when the load from the AC is on it.