dwhite93

So whenever I have my air on ac/heat and im stopped, my idle will always jump up and down and every blue moon the car will cut off. Someone told me that I needed to clean my throttle body and that would work but im not sure. NEED HELP. Thanks in advance.

Z28KLR

By how much does idle fluctuate?

A little bit, say maybe 100 rpm or so as the compressor cycles on and off is normal. When it comes on, the Idle Air Control valve opens up a little to maintain idle speed (750-850 rpm) to compensate for the load placed on the engine by the compressor.

Keep in mind that the compressor runs in both the A/C and Defroster positions on the hvac control panel.

If the idle is more erratic than I described, possibilities just off the top of my head would be vacuum leak or other source of unmetered air coming into the engine, malfunctioning IAC, maybe even just a "tune up" item related issue.

dawson1112

Its normal for the idle to change momentarily when ever the ac compressor kicks on, but it will fluctuate more and more as the IAC becomes dirty or starts sticking. To a point it will cause your car to stall sometimes. Ideally the idle should change so little that you don't even notice it, but if the iac is starting to go bad or is dirty and slow to respond it will get worse and worse.

tadpole1969

it maybe your ac low pressure switch
it will cause your problem

best way to test it is like this image below first do the wire jumper then crank the car and turn on ac full blast it should idle fine if it was bad , dont run it long like this ! just long enough to test it >>>