RPM's with a/c

[TheApocalyptican]

Going to be buying my tuning stuff soon,and wanted to start learning and looking over stuff now. I was looking over the $42 bin file from this site for a 1227747, and saw both: RPM added to desired idle w/AC on, & RPM added for A/C On. The first has a value of 0, and the second has a value of 25. Why are there two different settings? Do they both need adjusted in some way, or is just the second necessary?
I want to raise the rpms with the a/c on because it makes the a/c work better, and during the summer here in Vegas, the colder the a/c the better.

[PJG1173]

one of the things you have to keep in mind is the descriptions were made by the user community so sometimes there is some ambiguity in some of the xdf's. I have a different PCM and I have idle rpm A/C on P/N and idle rpm A/C on in gear. some times you just have to experiment with the settings and see what they do. I suspect it may be one for ingear and one for out of gear. is the bin for a manual trans?

[EagleMark]

There's actually 6 different scalers for A/C. The 2 you are talking about are for idle and desired idle, Idle would be neutral or open loop. Desired idle would be for Closed Loop idle in gear.

They all work well as is to keep a good steady idle while the A/C compressor kicks on and off. If you have a manual trans raising the RPM is fine. But please take a warning of raising the idle in an Automatic trans! If you raise the idle with A/C on, and are sitting at a traffic light stopped with foot on brake and A/C kicks on and idle increases to much you start to roll into the car in front of you if you do not apply more brake pressure.

These settings are not to make idle rise, but to keep idle steady while A/C compressor kicks on and off. They are useful for off roaders who have on-board air and want idle higher when air compressor is running. But that is always in park or neutral.

[TheApocalyptican]

I figured there had to be a difference between the two. I appreciate the warning, but during the middle of summer here, the a/c almost never kicks off, so it switching back on isn't much of an issue. I did this same thing last summer with the idle screw, and it made the a/c work so much better. I learned however, that with the base idle changed, it messes with the computer, and can make the computer actually pull timing. While I'm not sure if it will actually pull the timing, what I was reading about the computer wanting a specific rpm made sense, so now, I'd like to do it the right way and bump the rpm up some AND let the computer know that is the way I want it.

[EagleMark]

Sounds like a good plan.

I'll tell you I have a 1990 Suburban with four core radiator and shroud with clutch fan. It will idle in parking lot with A/C on at near 100 degree days and keep car cool and not overheat, leaving grandma and dog in truck while we shop. Having good fan and shroud to suck air over A/C condenser is imperative to good cooling at low speeds.

I've also seen guys on net use water injection sprayer nozzles to spray a lite mist of water in front on condenser at idle to further cool when at stop? Like an evaporative cooler (swamp cooler) patio misters and such sold in AZ and areas like you are in. It evaporates before ever coming into engine compartment.

[TheApocalyptican]

I've too got a 1990 Sub with a 4 core and shroud with clutch fan. Also has pushers on the evap in the front. No overheating problems at all this way! I am however running r134a, and I have found that just adding a little rpm...to say like 700, makes the a/c ice cold at idle. The biggest problem here in the summer is that we've got that 100°+ heat, and then all the concrete and blacktop, and I'm sure the asphalt is probably 130°+! Best solution would be to move somewhere cooler, lol.

Thanks for the help on this. Probably will be back with a question or two once I actually start tuning.