I've spent the day attempting to diagnose the following symptom:

The a/c compressor will engage for about four minutes and shut down. It won't come back unless the vehicle is shut down and restarted.

I have done the following:

1) Checked the low pressure switch. Found a ground on both terminals when connected to 12V.

2) Isolated the system from the Klima. Removed the Klima and installed an ice cube relay in it's place.

No change in symptoms. Four minutes of compressor engagement and then it drops off line.

I'm at a loss as to what other device would control the compressor engagement. AFAIK, there is no high pressure switch that shuts it off???

Any additional thoughts would be greatly appreciated.