Hi...My 03 ml500 overheated the other day. I did some checking and noticed that the radiator fan does NOT run at a high speed when the AC is turned. It just runs at one speed which is quite slow.

I read a few posts here that indicated the problem could be the radiator fan assembly which is about $1000. Before i bought the fan i wanted make sure the problem was not somewhere else. So i unplugged the coolant temp sensor right next to the thermostat housing and started the car. The fan came on immediately and ran at a very high speed.

SO, i am i correct in concluding that the radiator fan is NOT the issue here ? I am thinking it could be the thermostat and /or coolant temp sensor. If the thermostat is stuck is there a chance the temp sensor is not picking up the correct temp in this case ?? Please comment. Thanks

smk_texas
03 ml500 96k
98 s420 90 k
95 e300d 337k