Recently, I noticed (while installing a new battery) the aux fan connector located under the battery tray and was not connected. It appears to have been left disconnected for some time because the male connectors were oxidized.

I re-connected the aux fan, and about a week later, the charge indicator light started to give faint glow visible only at night. I re-tested the alternator and it is fine (recently installed new regulator). Soon the charge light would come on and glow brightly for a few moments and go back out. Now, it stays on all the time and gets brighter as the RPMs increase. The battery still has a good charge and the car still starts every time, just like it used to....

Could the aux fan been disconnected because the PO noticed this 'short' and was too lazy or cheap to fix the problem? Would an electrical problem in the aux fan cause this problem? I haven't disconnected the fan connection yet because I was waiting to see if the problem was the battery. Also, the AC drier/reciever is frozen on this car, so I really never had need to use the aux fan... the temp has only gone above 105C once in the past 5 years. I want to get the AC fixed so I will need the aux fan to be operational... right?

Thanks for the help

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William
76 240D (W115) - 550K miles
78 300D (W123) - 200K+ miles

IF you replaced the regulator, you may have an overcharging problem. The light is an idication of problems. If the fan goes south, it will usually pop the fuse and not interfere with anything else.

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Benzmac:
Donnie Drummonds
300E
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks Donnie,
I have a spare alternator in the garage. I'll trade it out this week and see if things change. I am not sure of its condition. I will probably have to get a Bosche re-man.
The fan fuse is fine... I disconnected it last night and the light was still burning bright. Obviously not the fan causing the problem.
Thanks for the insight

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William
76 240D (W115) - 550K miles
78 300D (W123) - 200K+ miles