I tried the ac for the first time and the compressor wouldnt engage, so I assumed low on freon. Had the system evacuated and recharged at the shop. The clutch will engage for 2 seconds (with no or very little compressor rotation) and then drop out for 3-5 seconds. The mechanic shorted the low presure switch with the same results. He was able to rotate the compressor manualy so it is not locked up. My question is this: Are there any other safeties involved or do I just have a bad clutch

I tried the ac for the first time and the compressor wouldnt engage, so I assumed low on freon. Had the system evacuated and recharged at the shop. The clutch will engage for 2 seconds (with no or very little compressor rotation) and then drop out for 3-5 seconds. The mechanic shorted the low presure switch with the same results. He was able to rotate the compressor manualy so it is not locked up. My question is this: Are there any other safeties involved or do I just have a bad clutch

There is a high pressure safety switch as well. It shuts off the compressor if the pressure gets so high that the emergency valve could vent.

What were the pressures in the system?