Cadillac Repair: 1991 cad seville ac, atmospheric air, ac system

Question
Took the car to a shop to have the freon switched to r134. He removed all the old freon... put the stop leak and oil in that needed to be put in and started filling the r134. He stopped after only putting in about 1/half of the can. Said the fan motor was out. This is not true but I don't think he knew anything about cads and their computer system.
After clearing codes I got the fan to come on but the low refridgerant compressor off msg still comes on. I checked the pressure and it is showing full.
How can I get the compressor to kick back on? I cleared all the codes according to the directions I got off this site from someone else and it still goes straight to econo mode.
thanks
Kathy

Answer
He has to evacuate all the atmospheric air from the ac system, Jumper the AC relay and add the freon.

Unfortunately this conversion does not always work as the check engine light for low freon keeps coming ON because the sensors are NOT calibrated for this new type freon.