Hi All,
Just purchased a 2003 SL500 with 59000 miles. The “AC OFF” lamp is on and when the button is pushed it blink a few time and keep stay on. I think the AC system is the problem, if anyone can email me (hxh_ym@yahoo.com) the diagnostic procedure or what to check for the AC would be appreciated. There are no CEL codes (no malfunction codes), the car seems to drive normal, just no AC cold air. That is for now, hope you can help out.
Thanks,
Hung

Diagnosis on that car & most MB's after 2000 requires using a scanner.

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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

to see if the amount of refrigerant in the system is correct.

After carefully compare the OBD II connectors and with a little force, I was able to connect the OBD II to the car. Performed the “Key ON Engine Off” and the “Key On Engine Running” code reading both results PASS with no trouble codes.

I tried to over charge a bit but didn’t help, released some freon to almost under charge also didn’t help. Will recharge with oil and freon again and hope for some luck.

Thank you for the suggestion so far. If you have procedure with steps to diagnostic the AC issue for 2003 SL 500 please let me know and I will try that procedure.

Thanks,

would be to take it to a good automotive A/C shop and have them remove the refrigerant and replace it by correct weight,