BMW Repair: air cond., r 134a, radiator support

Question
evan,
my son has a 1999 328is. the air compressor engages however the cabin temp is warm. added freon, helped at idle, but under power warm air.
thanks,
john

Answer
John, You need to accurately fill the A/C system. Your system capacity is on a green label on the underside of the hood or radiator support. I believe the capacity is 1.63 lbs. I recommend evacuating the system of refrigerant and place under vacuum for half hour. Hold vacuum for 15 minutes. Make sure pressure holds and there are no obvious leaks. Add an ounce of Refigerant oil with dye in it to aid in future leak detection. Then charge the system to proper fill level (1.63 lbs?) with R-134A. Duct temperature should be 40-50 degrees after 3 minutes on max cold recirculation on and engine @1500RPM.
-Evan