no aux fans, '99 500sl
 

Last week the AC on our '99 500sl stopped working when the car was at low speed and at idle. No codes on the AC system. With help from a MB list, narrowed it down to the aux fans not coming on as the probable cause. Can anyone help troubleshooting why they won't work? The aux fan fuse is good. I assume there is a pressure or temp switch that is not working, a broken wire, and I've read about a rheostat on some MBs, but don't know what to look for or where in the engine bay. Any help is appreciated.
Pete

You have either an incorrect year or model ....

'99 is a SL500
500SL is '93 and before ..

They have different aux fan circuits..

a/c 500SL
 

Check the fuse for the aux. fan.
Make sure fan(s) isn't stuck,If it is replace.Test by applying power to fan motor.
Check operation of aux. fan relay. Jump pressure switch wires (pigtail)on rec./drier. Listen for click at relay. look for power at fan wires.
Mike

That would be correct if he has a 500SL..not if he has a SL500...

thanks for the quick responses,
my bad, it is a '99 sl500 - typing faster than thinking. Where exactly are the fan relay and pressure switch located? The fuse is okay, both fans spin freely. Hard to find a good place to put power to the fans