A/C compressor cycles on and off every 3-4 seconds

This could be a couple of things.

You could have overcharged the system. What pressure were you seeing after you added the R134?

This would cause the compressor to kick on and then off shortly afterwards.

Let me know

Sean

Instructions on can said pressure should be between 45 to 55 lbs. When the ambient tempature was 85.

What size can did you add to the system? Did you purge any of the air before hand or use a vacuum to recover the refrigerant before?

The system should be around 28-30 with the compressor engaged, and 40 to 45 after it cycles off.

This also could be a couple other things, try this. Apply throttle to about 1500 rpm's and see if the clutch stays engaged.

Sean

I did not purge the system. I just assumed it was low and added. The can is 18 oz. But very little went in before I reached pressure. Tried raising the rpm, doesn't matter. Compressor just keeps kicking on and right back off after a few seconds.

Related question: How do I purge the system to just start fresh? Any help appreciated.