Drove 500 miles in rain/sleet last night, got in at 2:30 a.m., turned off the key and the auxiliary fans came on and stayed on. Car ran great all the way, engine temp where it should be, fans will not shut off unless I turn the key back "on". Since it was late I pulled the fuse for the fans. The kid has my service CD ... No climate control unit codes showing when I run the diagnostic. Any ideas of where to look first? Thanks!

Ha! Turned out it was low on coolant. Replaced the water pump about a week ago, thought I had all the air out of the system but apparently it took a good long drive to purge it all. Don't know why I didn't get a low coolant warning. Temp gauge still showed 80C. In any case, added another 1/2 quart and all is well.

That's interesting... I've gotten the low coolant warning on my car but the fans have never behaved that way.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Same here. No low coolant warning but coolant level was near the bottom of the reservoir. Might not be specifically related to the coolant level itself but to whatever thermal switch sets the fans off. Definitely odd, but two days and 500 miles later the coolant level remains full and the fans are off when they should be. Will have to review the CD to locate the sensor - if indeed it's a separate sensor - that turns the fans on. It's never dull