I recently bought a 97 Ford Ranger from a guy at work, and he said the AC was working fine until they swapped the motor and just never got around to charging the freon. So I bought a can of freon today and as I began putting the freon in the comp the compressor clutch started to lock up almost in rythym.

At first it was running just fine until I put the freon in (to the right place on the freon meter of course) and then it would just lock up at frequent intervals. I used the R134A Freon. Also I don't know if it matters or not but the gauge jumped between green and yellow while running and whilst not running it would land a bit in the red on the freon meter.

Any help would be greatly appreciated.