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,

How can I visually tell if the AC compressor kicked in for 2003 SL500?
Does this model AC compressor have the clutch that can be turned by hand?

The reasons for my questions were that I can’t turn off the “AC off” lamp at the climate control, it will blink slowly three times and keeps stay on, I am still not sure of the problem, but this may have caused the AC compressor not to kicked in. I have been trying various setting but have not able to turn the “AC off” lamp off.

I tried to spin the AC compressor clutch (not sure if that is the clutch, the center of the AC compressor pulley) by hand but it didn’t move, but I can see it spins with the engine when the engine is running.

There is no error code read with the OBD II, with engine running or just key ON.

I have check both AC LOW and HI pressures when engine running and while engine not running and there are no different in pressures, both LOW and HI stay at about 45 psi. This also indicates that the AC compressor is never kicked in, right?

Any suggestion that I can beside take it to the dealer?

Regards,
Hung

Carsoft 7.4 multiplexer interface works with 2003 SL500 R230

Successfully installed with an older desktop running Window XP, connected from desktop serial port to 2003 SL500 OBDII connector. Able to erase all errors (12 total). Finally able to clear the Airco error, the “AC-off” light is off now, and able to recharge the AC (although the AC is not very cold yet, but will work able to DIY now). Three errors returned after cleared, will ask for help when needed in a SL R230 thread.

Tried with a newer laptop, also running XP, using USB/serial cable, none of the USB ports worked with setting COM1-4. If anyone has this configuration work please describe the procedure.

Will buy the PCMCIA to Serial adapter card and try with the laptop again.

The Carsoft software installation is a bit tricky, need to be very careful with each step. The last step of the 2nd installation part needs the activation code, I skipped it as I don’t have the code.

Overall the product features well worth the $120 or so…

Regards,