The AC compressor doesn't like to come on, especially when the truck is idling. When idling, the truck will bog down to 400RPM when the PCM calls for the compressor but doesn't get it, then repeat every 10 seconds or so. Sometimes when I give it some gas, it will come on for a while. Most of the time, it just doesn't work. Sometimes when I look under the hood and open the throttle with my hand, the pulley will turn like 1/4 of a turn and stop. I topped of the refrigerant and added a can of oil. Could the clutch be bad? Is the clutch serviceable? I'm thinking that's the problem, but if anyone has any other ideas or experiences, please let me know.

 

Try cleaning the throttle body to get the idle back up to normal. The compressor wont come on if it's idling that low.

 

It idles at 600, but when the PCM calls for the AC Compressor, it bogs down to 400 for about 1 second for some reason. I was reading on the software forums and it said something about the IAC's being out of line will cause this and it's common with aftermarket cams. Maybe I'll find out how to fix it soon.

 

Is the pressure at a reasonable level? If it's too high, it'll cut out (primary and/or secondary switch). Don't add the oil unless the system is totally drained. If you overfill with that, you'll stress the system. Been there... done that... There's also a low pressure switch, but I'd rule that out if you recharged the system to the recommended level. If you're giving it gas, and it comes on, pressure should be fine. One true way of checking switches is to bypass each switch, and "jump" the wires. I did this when my low switch was bad to get me home from a 150-mile trip. You could do this temporarily to rule them out.

Otherwise, I'd look to increase the idle to ensure you're not idling too low to run A/C given that you have an aftermarket cam. I don't know the specs, but did this start right after the cam swap or just all of a sudden?

 

It's been doing it for a while, just never bothered me until it got hot outside recently. Looking back, yeah it's probably since the cam. It's a TR220 in a 6.0, so I didn't think it would affect things too seriously, but I guess I was wrong. I hooked a meter thing up to the AC port, and it was in the "OK" range. It was in the "Recharge" range before I added a can, but with 160k+ miles, I could understand it needing it. There was no leak, it still blew cold, just was a little low on refrigerant. I thought maybe the low refrigerant was causing the compressor to not come on, but guess I was wrong. I probably shouldn't have added the oil, but too late now I'll log the IAC numbers tonight and see. I read on another forum that 600 was a good number for idle. Does that sound about right? I'll also see how raising the idle a bit affects the numbers. I hate to raise the idle because I don't want the truck to roll unless I hit the gas, but if it's neccesary to get my AC, I'll suck it up and do it. If anyone has any input or experiences, please post.

 

I recently had a similar problem. Took it to a shop and they replaced the low pressure switch, topped off the freon, and adjusted the compressor air gap. The fact that you say that "the pulley will turn like 1/4 of a turn and stop" makes it sound like the air gap could be your biggest problem.

 

i'm haveing the same problem!!

 

I should have said compressor CLUTCH air gap.

 

Yup same thing has been happening to myself as well and a friend I know but his truck is completely stock.

 

read on ls1 truck that its the clutch and something to do with air gap.