Thanks for the reply. I have the OBD II AutoScanner, but the connector seem to be different with the SL500. What type of scanner do I need, where can I get it and how much about it costs for a simple DIY model?

Note that the Malfuction information screen indicates "No malfuction". When I tried to push the "AC off" button, the lamp blinked slowly three times and kept stay on. I got only warm air even when I tried to turn the temperature knobs to blue (all the way cold) level. The compressor's clutch seems engaged when the engine running, but the air condition lines felt warm.

Regards,
Hung