BMW Repair: ac problem, hot summer day, 2000 bmw 323i

Question
My wifes 2000 BMW 323i has major air conditioning issues.The passenger side air conditioning vents blow air, but do not blow cold air. The drivers side vents blow slightly cold air (they blow really cool air if it is a cool morning), however, really have a hard time cooling down the car during a hot summer day, occasionally the fan seems to cuts off all together and I will cut it off for a few minutes and when I turn it back on the fan comes back on.  I have replaced the outside temp sensor and it seems like it might have helped a little with the cooling problem but not much.

Answer
Kevin, sounds like the car is low on refrigerant (system leak) and you have a faulty final stage resistor for the heater blower motor. Replace final stage unit, and check a/c components for oily discharge build up on them. There is an updated intake line to the compressor that has been known to cause unfavorable noises and leak (PN 64 53 6 933 368 for your application) Evacuate system and see if it holds vacuum, then add an ounce of PAG oil with tracer dye to make leak detection easier in the future. Then recharge system to capacity and retest operation.
-Evan