idle drop when Ac engage

[raycor178]

good day to all, whats causing this if the idle drops to 450 to 500 rpm if I turn on the AC on? idle at 750. when Ac engage, it drops to 450 t0 500 rpm and goes back immediately to 750. I am thinking of the AAC valve or FICD, please help thanks

[gotak]

Well I am thinking it drops because the AC take engine power to run. So when you first turn it on the engine RPM drops until the computer compensates for the extra load.

[nismo4life11]

+1 on that response

[nametakennow]

Right, the AC compressor runs on the accessory belt connected to your engine. When the compressor kicks over, there is an increase on "drag" (if you will) on that belt and, in turn, on the engine. The ECU quickly compensates for this increase. The drop is completely normal and happens in pretty much every car I've ever been in, though it's very noticeable in Sentras, probably because of the poor grounding in the electrical system.

[raycor178]

thanks to all your input guys. well maybe im just uncomfortable if the idle drops because it really trembles the engine. maybe should I raise additional rpm around 800? will it cure the problem guys?

[ianh]

Try cleaning the IACV it should idle up when A/C engages.

[nametakennow]

Idle should be a little higher after the initial drop, yes. Forgot to mention that.

[raycor178]

after the idle drop when AC engage, it quickly return again to its usual rpm i.e. 750. it does not add a little rpm.

[nametakennow]

Sounds like your grounds are probably better than most. There is nothing wrong with your car.