# rpm drops when AC engage



## raycor178 (Sep 2, 2008)

good day to all the members, I am newbie here, may I know what is the cause of my cars idle dropping when the aircon engage? at idle with no AC, rpm is at 750, when I turn on the AC, it would drop to 450 to 500 rpm that causes the engine to shake and it return immediately to 750 rpm. I am thinking of the FICD or AAC valve that is not working. Please help, its uncomfortable if engine is shaking everytime the aircon engage to on. thanks


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## GreenEyedAngel (Aug 22, 2008)

Is this when u first start her up or after she's warmed up? The engine shakes when the AC is kicked on? Is this just your sensing the condensor kicking on? The AC is going to draw on this engine hard - it is rather underpowered until it warms up for the AC.

Couple other thoughts - check the timing - 750 to 450 sounds odd to me unless engine is cold. Also - have u checked the spark plugs?


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## raycor178 (Sep 2, 2008)

yes after the car has been warm up, temp is already at the mid pointer, the idle is 750 or sometimes at 700. its unstable. And when i finally push the AC button to on position, the rpm drops quickly to around 500, sometimes 450 and it goes up quickly to its 750 rpm position. the dropping of the rpm causes the engine to shake when reaching to 500 rpm. is there a way that would increase the rpm at least 800 when I turn the AC on? would be the dropping of rpm be avoidable? i just read the work of the FICD and the AAC valve that they will increase more air meaning increasing the idle during AC on, headlights on, turning the sterring wheel, and others. so that the dropping would be avoidable and also the trembling of the engine. please advice, thank you in advance


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## raycor178 (Sep 2, 2008)

and yes the spark plugs are ok, thanks


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## topz (May 15, 2006)

Take your IAC valve off and give it a thorough cleaning with carb/injector cleaner. Most probably it'll cure your problem.


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## raycor178 (Sep 2, 2008)

thanks topz, i will try to do what you had suggested, thanks


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