It could be various things.

The first thing you should check is the air filters to make sure they are not clogged (or as the other message states that the intake air ducts are properly connected)

Then check is whether the AUX electric fan is running - the one in front of the rad.
That should be running when the AC is on if there is any significant heat load on the system.

For your model year I think you have the variable speed fan that is controlled by the engine computer.

If that fan does seem to be operating then you probably have a problem with either the expansion valve, or the charge in the system. In either of these cases you will need a person who knows how to maintain a BMW AC system. Getting the correct charge, and bleeding it to get the correct performance is specific process.

Another easy thing to check is the condition and tension of the compressor belt (check from below the engine).

You might also want to verify that the rads are clean. You have to unhook the main rad at the top and then lift it up and backward to see between it and the AC rad in front of it. It is not unusual for dirt and debris (leaves) to clog up the flow through the rads).

Also (there is always another "also") make sure the blending dial in the centre dash vent is not set to 3 blue (never leave it at more than 2 blue)

Cheers
Jim Cash

• A/C question 99' 540i - ryan32591 2008-08-19 20:27:24 (152 views)
  • Re: A/C question 99' 540i - cal45fan 2008-09-24 00:54:31 (48 views)
  • Re: A/C question 99' 540i - ryan32591 2008-09-15 21:05:33 (76 views)
    • Re: A/C question 99' 540i - jimcash 2008-09-16 10:19:24 (83 views)
  • It sounds like the compressor has enough refrigerant to - JoeC 98 740il & 750il 2008-08-28 20:02:54 (79 views)
  • Re: A/C question 99' 540i - ryan32591 2008-08-28 19:27:06 (83 views)
  • Re: A/C question 99' 540i - jimcash 2008-08-20 14:50:26 (111 views)
  • Re: A/C question 99' 540i - rick540 2008-08-20 12:06:41 (85 views)