GMC Repair: 1999 GMC Yukon Air Conditioning, gmc yukon, ac compressors

Question
How much refrigerant does 1999 GMC Yukon 2wd vehicle hold?  Attempting to recharge the system.  Do I use R134A with or without oil?  I've never recharged an ac system before.  Any specific precautions?  Bought a pressure test gauge and vehicle showed low (needing charging) on the low pressure side of the compressor--only low pressure fitting I could find for charging system: is this correct?  Condensors are noted warm to touch after running ac for considerable length of time--output warm in vehicle: am I on the right track? Just don't want to damage the vehicle for lack of knowledge.  Hope you can help my inexperience.  Thanks, Chris  

Answer
Hi,Chris

On a fully discharged ac the yukon takes 2.00lbs of R134a,now you still have freon in the hvac,you will need to add a little at a time to the low side{suction side}depending on ambient temp lets say 75-80,the low side should be at 32-35 psi ac on engine at idle,you dont need to add oil,only if you are replacing a componant,now keep in mind,ac systems are a closed system,if it is low on charge there is a system leak,ive seen many ac compressors fail on these trucks,so you may want to look into that,let me know if you need more help,Thanks


ED