Hi,

I have a 02 trailblazer LS with 70k miles, when i turn a/c on, the idle will kick below 500rpm and jump back to 700rpm, i think its idling to low when the a/c kicks in and out, seems like it wants to stall almost, it doesnt do it when the a/c is off. also it seems when i go in reverse and go to put back in drive the idle will drop really low also and has stalled a couple of times from it, any help be appreciated..does my truck have a maf sensor? i cant find it if it does

 

I believe there is a port in the throttle body that the computer uses to control the idle air supply. Usually idle problems are caused by this port getting gunked up with carbon from reversion in the intake. Not sure where it is on the TrailBlazer but if you can find it, clean it and that will probably fix your problem. Not sure about a MAF sensor but bet it has on somewhere between the filter and the throttle body.