How often should the compressor be switching on and off while at idle speed? When the truck (1987, 179k) is idleing the compressor seems to be 'jogging' on and off about every 10-15 seconds. I originally thought my rig suffered from the same a/c idle up problem I have read about in the archives, but now I'm wondering if it is something to do with the compressor. When it kicks in the idle dips for a second and then regains composure, but just as the idle settles down it kicks off and the idle bounces again. This cycle repeats ever 10-15 second making the idle very rough and seemingly an a/c idle up issue. Any suggestions here would be greatly appreciated.