BMW Repair: AC problem/question, snow flake, center vent

Question
Evan,

The vehicle is a 2000 BMW 528i with about 63000 miles on it. This condition happens only when outside temp is above 80 degrees. In the mornings when temp is around 65-70 there is no problem and the AC blows cold air. It only happens when the outside temp is 80 or more and the car has been sitting in the sun for a while.

Thanks much,
Saeed
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Followup To

Question -
Evan,

MY AC is working strange! When outside temp is high (over 80) and I start driving, when I turn the AC on, it blows warm air, but after constantly driving for about 15-20 minutes it works fine and blows cold ait. Any idea? Thanks much in advance.

Saeed

Answer -
I need more info on the vehicle you are working on and any other information you can think of.
-Evan

Answer
Saeed, the a/c should blow cool air after a maximum of three minutes at 1500RPM with the snow flake lit and the control knob wheels and control unit temp set to cold. Don't use the recirculation button until the interior has cooled off from absorbing all that heat from sitting in the sun. Please check to see if the A/C compressor clutch is engaged and spinning with the drive belt. Am I to understand that the blower speed is not an issue and is correct at all times? Properly working A/C systems should blow between 40-50 degrees well before 20minutes of driving. Use a thermometer in the center vent to measure duct outlet temp. How cold does it get once the system starts working? I would have the refridgerant in the A/C system removed, measured, and recharged if the compressor clutch doesn't engage very shortly after engine start up. Also check for Electric fan operation. Electric fan in front of radiator should always be on when the a/c is on. If not the issue may be the fan (known to have issues on E39 models). Also check to make sure your outside temp sensor reads correctly on your dash. There are some things for you to check.
-Evan