AC Compressor Clutch

[rsilva708]

For awhile now, my AC compressor clutch has been engageing on and off about every 20 seconds. This happens no matter what the controls are set to. Today since we had a break in the weather, I hooked up one of those cans of AC recharge with a gauge on it, and the compressor is cycling on at 19 PSI, when the clutch engages, it climes to 40 PSI, and shuts off then the pressure drops back to 19 and the cycle starts again.

Anyone have any idea what the issue might be?

Thanks

2000 Explorer 4.0 OHV 4WD 92,000 miles