Not sure if this helps, but on the e53, if the front fan isn't working, the A/C won't work. Start your car, let it get to temp and see if the fan comes on. If not, then there is your issue. I bought my X5 and the dealer said "It doesn't have A/C that's why no one will buy it". I looked and saw the compressor so I knew it had A/C. Replaced the front fan, the A/C worked.

Make sure that's working before troubleshooting anything in the A/C system.