A/C Compressor Cycling Continuously even when A/C switch is off

I own a 2000 Jeep Cherokee, lately I noticed decreasing gas mileage and an erratic idle. At first I thought I just had a vaccuum leak. Then I listened carefully and heard the A/C compressor cycling on/off even when the A/C switch was in the off position. What could this be? A short? I removed the plug to the pressure sensor switch and this stopped the compressor from cycling. I just had the system evacuated a bit ago and filled up with r-134a. I am guessing I probably have a leak, which explains why the cycling is happening every few seconds. Thanks for any help.