Auto Air Conditioning & Heater Repair: RECHARGE, plymouth van, newer cars

Question
HELLO ! IS THERE ANY STANDARD PROCEDURE  TO GET THE SYSTEM COMPRESSOR TO COME ON AFTER LEAKS ARE REPAIRED,AND RECHARGING THE SYSTEM ?  ON THE OLD SYSTEMS ,I USED TO JUMP OUT THE LOW CHARGE SWITCH ,TO ALLOW THE COMPRESSOR TO DRAW IN THE REFRIG.,BUT ON SOME OF THE NEWER CARS ,THE SWITCH IS HARD TO FIND,OR DOESN'T EXIST. ON MY 1990 CADI,I DISCOVERD THAT IT WAS NECESSARY TO HOLD DOWN THE HEAT AND COOL SWITCHES AT THE SAME TIME ON THE DASH. I AM NOW IN THIS QUANDRY OF GETTING THE COMP TO START ON A 1993 PLYMOUTH VAN.THNX BILL

Answer
Hi William;
   Well, if you are trying to 12oz can load this unit, good luck.  I say that because modern systems like to be loaded completely before they will run, and gas loading from a can is a bitch!  (Your Cad is only the beginning)  It is possible to starve the compressor for oil when gas loading, which is why the makers ALL specify euipment to fully load a system prior to a start up.  I use a product called a dial-a-charge that allows me to fully load the system right from the get go.  You may need to have a pro do the actual charging with one of these or something similar.  There IS a cycling switch on the van, but it tells the ecm what to do and the ecm looks at lots of other things besides pressures to make the compressor work.  Ain't new cars fun ....NOT!
CarDocBill