Bob, Thanks- I will try and post on the MB site as well, I subscribe to Alldata, but the online manual is weak and the trouble charts are hard to see, not real good clear copies and then on top of that, the troubleshooting flow charts are weak to say the least. I have another manual coming in today that might help me also. I was trying to find a clear diagram of what the code considers as the so called compressor open circuit?? I will be testing the pressure sensor and refrigerant level tomorrow if I get home from work early enough. I'll post what I find then. Thanks again- JOe